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BAKFlip MX4 Hard Tonneau Cover - Folding - Aluminum - Matte Finish
(148 reviews)
Price: $1,249.99
In Stock
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BAKFlip MX4 Hard Tonneau Cover - Folding - Aluminum - Matte Finish
Part Number: BAK48121
In Stock
$1,249.99
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- All Info
- Reviews (148)
- Q & A (0)
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BAK Industries Tonneau Cover - BAK48121
Highlights
- Custom Fit for Your Vehicle: Secures to your truck bed with model-specific clamps and hardware
- Hard Cover Keeps Gear Safe: Locking panels secure when tailgate is closed to protect cargo.
- Full Bed Use: Quad-fold design flips up or folds forward for total bed access.
- Handles Weather Year-Round: Matte rubber seals and drainage system help keep water out.
- Built to Last: 1/2" thick rustproof aluminum panels support up to 400 lbs evenly.
- Low, Clean Look: Matte finish resists UV, scratches, and sits flush inside the bed rails.
Features to know about
Works Hard All Year: Aluminum Panels with Matte Finish
The MX4 uses ½" thick, rustproof aluminum panels with a premium density foam core for strength. Each panel is rated to hold up to 400 lbs of evenly distributed weight, so you can load gear or boxes on top without worry. The matte black finish resists scratches, scuffs, and UV rays, so it keeps its look even after years in the sun or through harsh conditions. It’s a solid choice for anyone who needs a cover that lasts through work weeks and weekend trips.
Full Bed Access When You Need It: Quad-Fold Design
You don’t have to take the cover off to haul taller cargo. The MX4’s quad-fold design lets you flip up sections for partial or full access to the bed in seconds. When you need the entire bed open, prop rods secure the folded panels upright at the cab so you can drive with the bed fully exposed. That means you can load lumber, coolers, or bikes without removing the cover.
Keeps Cargo Dry and Secure: Built-In Drainage and Automatic Latches
Matte black rubber seals and a built-in drainage system help keep water out of the bed during rain or washes. Automatically latching panels lock down when the tailgate is closed, creating a secure truck bed that protects gear from both weather and theft. The rear seal design lets you open and close the tailgate whether the cover is open or closed—no need to lift it first.
Clean Look, Easy Fit: Low-Profile Inside-Rail Mounting
This cover sits flush inside your bed rails for a low-profile look that blends well with the truck’s lines. Because it mounts inside the rails, you keep access to stake pockets, tie-downs, and accessories like ladder racks or raised rails. Installation is simple with no drilling required—frame rails clamp in place, and bolts secure the front hinge rail for a snug fit that stays put through daily use.
Expandable Storage Options: Compatible with BakBox2 Toolbox
When you want extra organization without giving up bed space, the MX4 works with the optional BakBox2 storage box (sold separately). It folds flat when not in use or turns into a handy shelf for smaller gear. This setup keeps tools, straps, and small items easy to reach under the sturdy protection of the MX4 cover.
Specs
Material and Construction
- Panel Material: 1/2" thick, rustproof aluminum
- Panel Core: Premium density foam core
- Rail Material: Aircraft-grade, rustproof aluminum with black powder coat finish
- Finish: Matte black
- Seals: Matte black rubber seals with built-in drainage system
Design and Functionality
- Style: Quad-fold
- Mounting Style: Inside bed rails
- Profile: Low-profile, flush mount
- Opening Mechanism: Fold-up design with prop rods for upright securing
- Latch Type: Automatically latching panels
- Tailgate Operation: Opens and closes with the cover open or closed
- Compatible Accessories: Stake-pocket-mounted accessories and raised side rails
- Accessory Compatibility: BakBox2 (sold separately)
- Rack Compatibility: Ladder racks such as TruXedo Elevate and Thule TracRac SR
Weight Capacity
- Rated Load Capacity: Up to 400 lbs of evenly distributed weight
Dimensions
- Folded Height at Cab: Approximately 5" above bed rails
- Folded Length from Cab: Approximately 26" - 28"
- Bed Clearance Provided: 21" inside the bed
Installation
- Installation Type: No-drill
- Rail Attachment: Clamps to the inside of bed side rails
- Front Hinge Rail Attachment: Secured with included bolts
Performance and Durability
- Finish Resistance: Resistant to scratches, scuffs, and UV rays
- Weather Protection: Matte black rubber seals and drainage system help keep water out of the bed
- Aerodynamics: Reduces wind drag to improve gas mileage
Warranty and Origin
- Warranty: 5-Year warranty
- Country of Manufacture: Made in the USA
448121 BAK Industries BAK Flip MX4 Hard Folding Truck Bed Cover
Replaces 486121
This Product Fits The Following Vehicles
- 2014 - 2018 GMC Sierra 1500 6-1/2 Foot Bed
- 2019 - 2019 GMC Sierra 1500 Limited 6-1/2 Foot Bed
- 2015 - 2019 GMC Sierra 2500 6-1/2 Foot Bed
- 2015 - 2019 GMC Sierra 3500 6-1/2 Foot Bed
- 2014 - 2018 Chevrolet Silverado 1500 6-1/2 Foot Bed
- 2019 - 2019 Chevrolet Silverado 1500 LD 6-1/2 Foot Bed
- 2015 - 2019 Chevrolet Silverado 2500 6-1/2 Foot Bed
- 2015 - 2019 Chevrolet Silverado 3500 6-1/2 Foot Bed
Ratings & Reviews
4.6
148 reviews
by:
Pete
11/14/2025
Pontiac
Trans Sport Van
BAKFlip MX4 is a great addition to any pickup. It allows for secure transport of material, keeping it dry in bad weather and yet readily accessible with the flip of a panel. It also keeps the weather away from your 5th wheel hitch. Can be left on when towing.
by:
Joe S
06/27/2019
Had it a if a year and this thing takes a beating and it doesn’t have a dent or scratch to show for it. I love it! If your contemplating, don’t! It keeps almost all the water out, except by the tailgate which is normal for any cover. Outstanding product!
by:
Mike K
06/19/2020
Love the look and the fit of the BAKFlip MX4 but after a light hail storm it is riddled with dents. My 2018 GMC has no damage but the cover does. Bummed.....
by:
James
03/28/2023
Easy to install. Doesn't leak. Easy to clean, and seems to have improved my fuel mileage a bit. I am happy and would highly recommend this cover. Fits my 2018 Silverado perfectly.
by:
Duane
03/09/2018
It’s worked great.
A fellow worker suggested it to me,
And one of my sons got one.
A second son is hoping to get one soon.
I always had a topper, so this is different,
But it’s been great and convenient.
A fellow worker suggested it to me,
And one of my sons got one.
A second son is hoping to get one soon.
I always had a topper, so this is different,
But it’s been great and convenient.
by:
Tim
10/25/2023
No regrets at all. We love this cover.
by:
Thomas
03/21/2023
Works great. No problems.
by:
Michael
11/23/2019
2018
GMC
Sierra 1500
A very well built product. Form, fit and function met all expectations.
by:
Darryl
06/19/2024
by:
John B
07/12/2026
I love how this tonneau cover works. because it allows use of almost the entire bed of the truck when it's fully open. I was a little disappointed with the clamps for installing the side rails, as they didn't seem as robust as the clamps in the cover I bought for my last truck. However, I am happy with its operation, and the fact that the truck bed is a locked compartment when I lock the tailgate.
Claire H.
7/14/2026
Thanks for the great feedback! We're glad you're enjoying the tonneau cover and that being able to use almost the entire truck bed when it's open has been such a big plus. It's also nice knowing your gear stays secure when you lock the tailgate. We appreciate you mentioning the clamps too—that kind of feedback is always helpful. Thanks again, and we hope you keep enjoying your new cover!
by:
Gordon
05/21/2025
2022
Ford
F-350 Super Duty
Bought it used.. I asked if it was complete undamaged.. It arrived complete including a scratch on the inside cover.. I'm glad it wasn't on the outside cover. Shipping was quick. Installation was fairly straight forward
by:
Doug
12/31/2025
Ordered the BAKFlip MX4 for my son on 12/15 after calling to verify the tonneau would arrive by Christmas. Then received an email that said "Your order has been forwarded to one of our partners for direct shipment to you" and never received another shipping update or any tracking info. Finally on 12/22 I emailed Etrailer.com who told me they didn't know when I would get it. The Tonneau finally arrived on 12/29, 3 days after my son returned to California (he drove his truck, 2100 miles). He won't be back till next Christmas so I have to figure out how to return this product. I had several other buying options to get this here by Christmas, but went with Etrailer because of their reputation. This will be my last purchase from Etrailer.com.
by:
David
04/10/2022
Overall, I am very pleased with my BAKFlip MX4. It has held up well after 1 year. It works well and looks good. It matches my matte black accessories and trim. It was fairly easy to assemble but I did have some tight fitment issues near the cab where the cover connects to the rail. I really like the security of the hardtop and access through the tailgate. Water is generally kept out, but sometimes there are water drips near the tailgate depending on the angle parked. So this cover keeps the bed *mostly* dry.
etrailer was very fast to deliver my cover, and it came in good condition.
etrailer was very fast to deliver my cover, and it came in good condition.
by:
Christopher
12/09/2025
The bed cover has been great so far. Followed the instructions and took my time adjusting it and it has been working well. Keeps the bed dry and looks good. I did have to order an extra kit to get enough rail clamps. Once I put the extra clamps on it feels much more secure. For 8ft beds they need atleast 8 to 10 clamps, not 6. The cover has been working in that I don’t have to uncover the whole bed to use it. I just need to open up as much as I need at the time.
by:
Chris B.
09/26/2020
So after a year I am still loving this bed cover. Had the fiberglass version for my 2013 F-150 and loved it as well, that's why I purchased this one for my 2019 Super Duty, it was also the first accessory I purchased for it because I was so used to my other one and knew I couldn't live without it. I never installed the drain tubes on either covers and still haven't had water get it my bed. Also the folks at etrailer are always awesome! Thanks again!
by:
Justin
04/23/2024
I have been using this cover for almost a year now, and am very pleased with it. It looks and fits great, and it is secure and keeps most of the bed dry in the rain. A couple of rubber trip bits have needed some improved securing, and I used a little RTV so it was easy. I drove it across the country round trip last summer and it was perfect. I would recommend this cover for a great-looking and pretty secure cover. Finally, it is easy to fold forward when it is time to haul loads taller than the bed rails.
by:
Rob
06/02/2024
Purchased this BAKFlip for my new 22 RAM Classic 1500. Installation went well, instructions were good to follow, and it fit perfectly. One of the plastic hold down clips had a manufacturer defect with excess plastic mold residue inside the clip that prevented it from properly working. I sent an online warranty claim explaining the problem, and a new clip was sent to me in a reasonable amount of time, and it worked fine. After one year of using the cover, I am very happy with it. Everything functions as it should, and it is very versatile. While it is not 100% watertight, I mostly notice a small amount of leakage around the tailgate seal after washing the truck. Under normal rainy weather, there is no leakage, and we get plenty of rain in the PNW. My four-star rating rather than a 5 star is only because of the manufacturer defect and the curling of one of the rubber cushions on the underside of one of the panels where the adhesive holding it on the edges has not held up under the hot weather (with the black color, when the sun beats down on the cover it gets pretty toasty inside the truck bed with the cover closed). I am thinking that should be an easy fix by applying some good adhesive and taping in place until the adhesive cures. Just haven't gotten around to doing it. Again, really like this cover. Would recommend it to others, and if I ever have a need for one in the future, would definitely not hesitate getting another BAKflip.
Rob
6/4/2025
The BAKFlip after 2 years is still functioning great. I fixed the curling cushion by applying some strong adhesive to the spots that had detached, taped it in place and let cure for a couple of days. That solved that issue. Would continue to recommend the BAKFlip to others.
by:
Michael
03/29/2026
Great tonneau cover. Fits as it should.
by:
Tianhe
03/26/2018
2017
Dodge
Ram Pickup
I installed the BAKFlip MX4 in my RAM 2500 Crewcab has the 6' 1/2 short bed, drived 300 miles now. good product, open and close the tailgate without lifting up the cover
by:
Gene
03/05/2026
dodge
Ram Pickup
Great fit on a Ram 2500 long bed. Everything stays dry on the inside.
by:
Jason V
02/28/2023
The cover functions ok. The tailgate leaks quite a bit. The manufactured edges that where cut were sharp and not painted or treated. The weather strip along the edges has already discolored/faded. Disappointed in the fading and less than ideal sharp edges. Somewhat expected leaks, but not this much. Average at best rating, especially for the price.
by:
Mike M.
11/21/2020
I am a huge fan of the BAKFlip. The installation was pretty straight forward and easy. Anybody with moderate mechanical ability can install. I think it took less than 2 hours. I live in a heavy snow area and had more than 24” of snow on it at one point and the product performed flawlessly.
by:
Greg
05/23/2026
Excellent product! Wait time was crazy but manufacturer is to blame on that one!
by:
Douglas
08/29/2025
I replace a camper shell with the tonneau cover because it is easier to remove when I want to put my pickup camper on the pickup. I am very happy with the cover and am glad I made the switch.
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See what our Experts say about this BAK Industries Tonneau Cover
- Best Tonneau Cover Style For Towing A Fifth WheelThe best tonneau cover option to use when towing is a retractable cover because it retracts into a canister so it doesn't block any of the view while towing. If you get a fold up cover it will block the cab window. If you get a roll up cover it will interfere with the trailer's overhang especially while turning. If you give me the year make and model of your truck I can make a recommendation.
view full answer... - Availability of etrailer Quad Fold Tonneau Cover for 2016 Chevy Silverado 3500Hi Bob; at this time we do not offer the etrailer Quad Fold Tonneau Cover for a 2016. We may come out with one in the future, but I don't have an ETA on when that might be since these are relatively new and a lot goes into adding additional fitment. The # e45DR only fits the 2020-2025 GM 2500/3500 with a 6-3/4' bed. Unfortunately, we don't have a low cost alternative for the 2016 either. The best I can offer right now for your Silverado 3500 is a tonneau cover like the BAKFlip MX4 # BAK48121.
view full answer... - Would BakFlip Tonneau Cover from Ford F-150 Fit 2015 Chevy Silverado 1500 6.5 ft BedTonneau cover fits are very specific. It's rare that a cover fits the same truck for more than a few years as the designs tend to change pretty frequently which means that there basically wouldn't be any cover from a Ford F-150 that would fit a 2015 Chevy Silverado 6-1/2 foot bed. For a BakFlip tonneau that fits your truck you'd instead want the part # BAK48121 which is a confirmed fit.
view full answer... - Rack For 2019 GMC Sierra 2500 With BAKFlip MX4 Tonneau CoverHey Charles, The BAKFlip MX4 Hard Tonneau Cover # BAK48121 or # BAK48122 for your 2019 GMC Sierra 2500 is compatible with one one rack that will allow you to carry a couple bikes, and that's the TruXedo Elevate. The right one depends on the size of your bed: - 6-1/2' Bed: TruXedo Elevate Truck Bed Rack System # TX46NV - 8' Bed: TruXedo Elevate Truck Bed Rack System # TX66NV The Elevate will essentially give you a roof rack at the rear of your truck, and the bars are adjustable, but...
view full answer... - Is Thule TracRac SR Compatible With BAKFlip MX4 Tonneau on 2015 GMC Sierra 1500 w/ 6-1/2 Foot BedIt is; the BAKFlip MX4 Hard Tonneau Cover # BAK48121 that fits your 2015 GMC Sierra 1500 is indeed compatible with the TracRac SR. The reason why is the MX4 installs inside your Sierra's bed rails, leaving the top free, and the TracRac installs on top of the bed rails so there won't be any interference. The correct part number for the ladder rack that fits your '15 Sierra with a 6-1/2 foot bed is the following: - Thule TracRac SR Sliding Truck Bed Ladder Rack # TH43002XT-781
view full answer... - Truck Bed Toolbox to Fit with BAKFlip MX4 Tonneau Cover on 2018 Sierra 1500 with 6-1/2 Foot BedActually we do carry a toolbox specifically designed to fit the BAKFlip MX4 tonneau cover, part # BAK48121, on your 2018 GMC Sierra 1500 with the 6-1/2 foot bed. It's the BAKBox, part # BAK92120. It can be folded down out of the way when you're not using it or turned into just a shelf instead of a box. I've linked a video for you to take a look at. It's with a different tonneau cover but it fits the same wth your MX4.
view full answer... - Height of BAK MX4 Folding Aluminum Hard Tonneau Cover BAK48121 When Folded Up Fully at CabWhen the BAK MX4 Folding Aluminum Hard Tonneau Cover # BAK48121 that fits your 2017 GMC Sierra 3500 with 6-1/2-foot bed is folded up fully the total height of all panels at the rear of the cab will be approximately 5-inches above the bed rails. My contact at BAK confirmed this height dimension.
view full answer... - When Fully Open Do Panels of BAKFlip MX4 Lean Up Against Rear of Truck CabYes, the panels do lean up against the rear glass of the truck that the BAK Tonneau part # BAK48112 that you referenced installs on. I attached a picture that shows what that looks like. I also attached a review video for this cover for you to check out as well.
view full answer...
- What Material are the Buckles of the BAKFlip MX4 Hard Tonneau Cover Made OfThe buckles that you see in the attached picture that are used to secure the tonneau it's folded, flipped up, or closed position are made of plastic.
view full answer...
- Will BAKFlip MX4 Hard Tonneau Cover Clear 5th Wheel Hitch when Closed on 2018 GMC Sierra 2500In all likelihood, yes, the BAKFlip MX4 Hard Tonneau Cover # BAK48121 will clear your 5th wheel trailer hitch when the cover is closed. The parts of the cover inside the bed that hang down only do so by about 1.5 inches from the tops of the bed sides. Worse case scenario is you may have to either lower the head on the hitch or just remove the head by unpinning it from the center section.
view full answer... - What Tool Box Works with the BAKFlip MX4 # BAK48121 on a 2018 Sierra 2500 with 6-1/2 Foot Bed? I have an answer for you. The DeeZee Red Label Truck Bed Tool Box - Utility Chest Style - Aluminum - 8 Cu Ft - Silver # DZ8546 does not fit your 2018 GMC Sierra 2500 with a 6-1/2 foot bed. However, for a 100% definite combination of the BAKFlip MX4 Hard Tonneau Cover - Folding - Aluminum - Matte Finish # BAK48121 and a tool box, I recommend using the MX4 with the BAKBox 2 Collapsible Truck Bed Toolbox # BAK92120. It clamps directly onto the bed rails so you do not have to worry about...
view full answer... - Dimensions of BAKFlip MX4/F1 When Folded Up on 2017 Chevy Silverado 2500 Short BedBoth the BAKFlip MX4 # BAK48121 and F1 # BAK72121 will take up about 26" - 28" from the cab-end of your 2017 Chevy Silverado 2500 short bed. So if your truck bed does measure 6-1/2' (which can slightly vary so you need to confirm on your end) then that leave you with about 52" - 54" of open space. The differences between these covers is that the MX4 has a matte finish on top of the aluminum cover while the F1 has a gloss finish and a fiberglass top on top of the aluminum cover. This helps...
view full answer... - Recommended Hitch For A 2019 GMC Sierra 2500 Denali 6.6' Bed With A Tonneau Cover The Curt E16 5th Wheel Hitch w R16 Roller for Chevy/GMC Towing Prep Package - Slide Bar Jaw - 16,000lbs item # C16667 will drop right into your OEM puck system and has an adjustable height of 15-1/4 - 18-1/4 inches. This will allow you to leave your hitch in place and roll down your bedcover. As for the Tonneau bedcover you have a few different options: For a retractable cover I recommend the Pace Edwards Switchblade Retractable Hard Tonneau Cover - Aluminum and Vinyl - Black Item #...
view full answer... - Recommended BAKFlip MX4 Hard Tonneau Cover for 2017 Chevy 2500 with 6-1/2 Foot BedWe just had BAK in last week and the BAKFlip MX4 Hard Tonneau Cover - Folding - Aluminum - Matte Finish # BAK48121 is the newest model they have available. The part number from the manufacturer matches what you are asking about, our part number is just slightly different. I've attached the installation details for you. They recently started making this model with a tail gate flange that allows the proper seal when you close your tailgate without needing to lift the tonneau. That is...
view full answer... - 2016 Chevy Silverado 1500 6-1/2 Bed Ladder Rack Recommendation to Fit with Tonneau CoverWe do have some ladder rack options to fit with the BAKFlip MX4 Hard Tonneau Cover # BAK48121 on your 2016 Chevy Silverado 1500 6-1/2' bed. I personally like the TruXedo Elevate Truck Bed Rack System # TX46NV because it uses standardized crossbars that have T-Slots so it's easier to install a wider variety of accessories. This installs using clamps like your current tonneau cover so you'll need to adjust your rails when you install this. If you're just needing a standard ladder rack that's...
view full answer... - Ladder Rack Needed for 2015 Chevy Silverado 1500 6-1/2 Bed with BAKFlip MX4 CoverSince your BAKFlip MX4 Hard Tonneau Cover # BAK48121 sits inside the bed rails of your pickup we do have some solutions for you. The best option would be to use the Thule TracRac SR which is a sliding rack that mounts on top of your bed rails and has a weight capacity of 1,250 lbs. To fold your MX4 up you will simply need to move the legs out of the way along their tracks. For your Silverado you will need either part # TH43002XT-781 or part # TH43002XT-781EX if you want the over-the-cab...
view full answer... - Recommended BAKFlip Hard Tonneau Cover For 2015 GMC Sierra Denali 2500 HD With 6 1/2' BedFor your 2015 GMC Sierra Denali 2500 HD with a 6 1/2' bed I recommend the BAKFlip MX4 Hard Tonneau Cover # BAK48121 due to it being all aluminum which will be extremely durable to the elements and keep the cargo in your bed secured unlike traditional vinyl covers that can be cut with a knife. The BAKflip MX4 # BAK48121 will offer 21" of clearance inside of your bed and has a very sleek folding design that will allow you to fold the cover when you are using your fifth wheel hitch and wont...
view full answer... - Recommended Ladder Rack That Does Not Interfere With Hard Tonneau CoverIf your Undercover Hard Tonneau Cover sits inside of the bed rails you would be able to add the Thule TracRac SR Sliding Truck Bed Ladder Rack # TH43002XT-781 which sits on top of your bed rails and allows the ladder racks to slide around on the base rails for more a customizable fit for a 2015 Silverado with a standard 6 1/2' bed. You will need # TH43002XT-782 if you have a 2015 Silverado 1500 with a 5 1/2' bed. To be able to fold the cover you will need to slide the legs of the ladder...
view full answer... - Would Tonneau From 2019 GMC Sierra also Fit 2015 Chevy Silverado 6-1/2 ft BedYes a tonneau like the BAK MX4 part # BAK48121 would fit both a 2019 and a 2015 Chevy Silverado and 2019 GMC Sierra 6-1/2 foot bed.
view full answer... - Tonneau Cover Compatible TracRac System For A 2019 Chevy Silverado 1500 Hey Mike, I can definitely help with this. You are correct that to make your TracRac tonneau cover compatible, all you would need to do is add the base rails and swap out the feet (modular sliders as Thule calls them). That said, the cost of these individual components can add up, and buying a whole new system does seem like the logical thing to do. You would need two of part # TA01-42004, two of part # TA01-42003, the base rail set # TH21781 and four of the knobs # TAKB-90030-1. With...
view full answer...
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Info for this part was:
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James
3/29/2024
After a year, the only issue that I have had with the BAKFlip cover is that the small pieces between the larger panels do not stay in place well, and the process of flipping the panels back down in place requires that you hold those connector pieces in place so that they settle correctly into place. I use some gorilla tape to hold them in place, but that shouldnt be necessary. Otherwise, it has been a great addition to the truck! I like being able to leave things in the pickup bed that are out of sight and dont fly out or get stolen.