Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 0719 pin boxes.
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Getting there is half the fun, right? Not if you're being bumped, jerked, jammed, and pushed around from the chucking, road shock, and bounce that occurs as you tow your fifth-wheel trailer or RV. And imagine the costly wear and tear on your trailer as it endures that rocky ride.
Put the fun back into your trip and ease the stress on your trailer by replacing your factory pin box with the Trailair Flex Air pin box. The internal air bag and built-in shock work together to cushion your ride, improve handling, and limit strain on both your truck and your trailer. But what sets the Flex Air apart from other air ride pin boxes is the addition of a pivoting head. This head, along with its built-in rubber compound, provides additional cushion, absorbs road shock, and reduces chucking for a significantly improved ride.
A heavy-duty rubber compound is built into the head assembly of the Flex Air pin box. This rubber is the first defense against road shock. It helps to absorb the bumps and vibrations experienced when towing a fifth-wheel trailer over rough roads. Standard pin boxes without any type of shock absorption transfer road shock to your trailer, resulting in potential damage to the trailer and an overall bumpy ride. The shock-absorbing rubber inside the Flex Air takes the beating so there's less wear and tear on your trailer or RV and you get a smoother ride.
Because the rubber may not be able to absorb all of the road shock that you experience, the Flex Air also implements air ride technology to virtually eliminate shock. When you encounter uneven terrain on your trip or hit a pothole on the highway, the Flex Air pin box compresses vertically, similar to how a pair of scissor blades closes in on each other. This compression transfers the road shock and vibrations to the internal air bag, saving your fifth-wheel hitch, trailer, and tow vehicle frame from enduring a rocky ride.
A built-in strut, or shock, controls the Flex Air's compression so that the internal air bag doesn't burst. The strut also causes the pin box to appropriately rebound without any bounce, and positions it to be ready for the next bump in the road.
The pivoting head on Flex Air allows for controlled back and forth movement of the king pin to reduce the uncomfortable jarring known as chucking. Unlike a rigid pin box that has little give at the point where the trailer and the hitch are connected, the Flex Air can pivot slightly to compensate for those times that your trailer suddenly pushes or pulls on your tow vehicle. Because the pin box head - not the king pin itself - is moving, the chucking that often occurs when the king pin jerks around inside the hitch is significantly reduced.
Simple Setup and Installation
First, simply remove your existing Lippert 0719 pin box from your trailer. The Flex Air uses the same bolts that held on your original pin box so no additional hardware is required for installation. Plus, the Flex Air pin box comes out of the box ready to be put on your trailer, so no assembly is needed. Because the Flex Air is quite heavy, you should put it on an elevated surface or have a friend help you support its weight during installation.
The internal air bag should be inflated after the Flex Air pin box has been mounted on your trailer. Using the air intake valve, inflate the air bag until the outer cylinder of the shock rises high enough to fully expose the yellow inflation indicator sticker.
Average Customer Rating: 4.5 out of 5 stars (52 Customer Reviews)
Flex Air drastically reduces chucking, absorbs road shock, and minimizes bounce. The internal air bag and built-in strut work with the rubberized pivoting head to achieve a dramatically smoother ride. Replaces Lippert 0719 pin boxes.Review from a similar Trailair Flex in Fifth Wheel King Pin
Pin box was just as I ordered. It does improve the ride. Won't make your truck ride like a Cadillac but does help. I was also surprised that it was shipped in a card board box that was coming apart when it got to me. A wooden crate I think would be better. 725583
Review from a similar Trailair Flex in Fifth Wheel King Pin
Awesome price! Being installed on a Grand Design 375RES. Shipment went great this is a heavy unit, arrived banded on pallets in excellent condition. Installation was simple and as instructions stated. Waiting for the next road trip to be able to test effectiveness. Always been a pleasure dealing with E-Trailer. 915470
Review from a similar Trailair Flex in Fifth Wheel King Pin
Product arrived in a timely fashion in an un damage condition. Quality was better than expected. Installation for me took about two hrs, with my wife helping. I placed the pin box in the bed of my truck with the help of a frontend loader and let it down on a floor jack. From there install was fairly easy. Pros: Good quality Heavy Duty Cons: You will need 3 or 4 strong friends to handle it No instructions included I did find a pdf on the bottom of the page however that listed the torque for 1/2" bolts 869755
Review from a similar Trailair Flex in Fifth Wheel King Pin
Great product and eTrailer shipped this heavy, large item very fast. Ordered on a Monday and delivered at the door on Friday!. Installed on my Grand Design but haven’t hooked up for a run yet. This is a very heavy unit (232 lbs) so get a team together to get it installed. 796232
Review from a similar Trailair Flex in Fifth Wheel King Pin
Excellent product although we haven;t yet installed it due to the manufacturer torquing the mounting bolts on our original pin box so tightly that I can't get them off. That is no knock on this product. I will be taking it to a dealer for mounting. I will followup for more comments when it's mounted next week. Looking forward to the promised smoother ride. The product arrived quickly and in good condition. 769619
Review from a similar Trailair Flex in Fifth Wheel King Pin
Increased a smooth ride by 100%. No more jolting when you drive over bumps in the road. I used to dread crossing state maintained bridges because of the enter and exits bumps, but not any more. Thanks e-trailer! 767467
Review from a similar Trailair Flex in Fifth Wheel King Pin
Since changing to the Flex Air, there is no comparison to the ride. Nothing out of place inside the RV after being on the road. Highly recommend this pin box, well worth the money to me. 766726
Review from a similar Trailair Flex in Fifth Wheel King Pin
In a word, my experience with the Flex Air has been so-so. I bought this product to eliminate a pretty severe chucking problem with my 5th wheel. While this has been a nice improvement, it did not eliminate as much of the chucking as I has hoped. Certainly not to the extent that you see on the e-trailer video for this product, where the bobble head on the dashboard shows almost zero chucking after FlexAir is installed. And yes, I do have a level ride, good weight distribution, and the hitch installed directly over the rear axle. So the typical causes of chucking have been addressed. The shocks do control the up and down motion pretty well, but the FlexAir doesn't do as good a job on the front to rear motion as advertised. Not sure this is really worth the expensive price that is charged for the unit. 761863
Review from a similar Trailair Flex in Fifth Wheel King Pin
Arrived in Excellent Shape!...having the new pin box installed today. 760592
Review from a similar Trailair Flex in Fifth Wheel King Pin
This new Pin Box was the Best Investment I have made since owning my 5th Wheel RV !!!! It has almost completely eliminated the "Chucking" of the RV/Truck combo while traveling over less than perfect roadways, and we all know how many there are in the South ! The Installation went exactly as the Instructions spelled out ! You will need a strong helper ! I built a wooden box to put on top of my Hydraulic Jack to make the lifting a much easier process ! I would recommend this product to anyone owning a 5th Wheel RV !!! 757537
Review from a similar Trailair Flex in Fifth Wheel King Pin
I bought the Flex Air to replace the standard Lippert pin box on our Cedar Creek fifth wheel that weighs 12K lbs. Just looking for something to smooth out the ride and the Flex Air seemed to have good reviews and recommendations. I went to the Lippert website to download the installation instructions because I couldn't get the link on the etrailer website to work. The instructions will give you the torque values required for installation and the air pressure for the inflatable airbag on the hitch. Installation was straight forward, but you better have a plan because this thing is heavy (300 lbs) and it will take some manpower to move around and install. 749960
Review from a similar Trailair Flex in Fifth Wheel King Pin
This is the best money I have spent on my camper hands down. My hitch weight is a bit over 3200 lbs. I use a PullRite Super Lite hitch, photo attached. Once locked on the king pin, four bolts are set from the adapter plate against the king pin plate. The plate on the Flex Air is twice as thick as the original pin box and I have way more confidence in a solid set of these four bolts. I was blown away by how this hitch absorbed road shock. I will never have another 5th wheel without this set up. 749458
Review from a similar Trailair Flex in Fifth Wheel King Pin
This is our second Flex Air. It really smooths out the ride for the 5th wheel on wavy or bumpy roads. 722990
Alfred R - 11/07/2020Review from a similar Trailair Flex in Fifth Wheel King Pin
This 250 lb item was shipped in a cardboard box that was just sitting on a pallet. When I opened the box I found the Flex Air was sitting upside down with the foam pad on top. I have no idea how the air filling nozzle wasn't damaged. Luck I guess. There were no "UP" markings on the box. No instructions were included. Installation went smooth, it's just heavy so be careful. Instructions and videos can be found on-line. The Flex Air is at least 4" taller than the OEM box that came with our Grand Design Reflection. I mounted the Flex Air as high as I could and lowered the receiver on the truck. The trailer is still nose high but seems to tow fine. My test ride was noticeably smoother. You can see a lot of motion on the Flex Air that would have otherwise been transferred to the truck. 722359
Steve t - 11/04/2020Review from a similar Trailair Flex in Fifth Wheel King Pin
Great product! Took 80% of the bucking out of the ride.It was an easy install and very happy with the results. Just came back from a 4,000 mile test drive and all is good. 706049
Review from a similar Trailair Flex in Fifth Wheel King Pin
Have not had a chance to take it for a road test yet. But it fit well, was easy to mount, the issue I ran into was getting the pin height. As my truck is 4x4, and the B&W hitch is as low as it can go, I still needed another 2 inches to get the pin box high enough, could not raise pin box any higher, and with the 5th wheel already at 13'4" did not want to lift the trailer, so ended up lowering the truck 2 inches to get everything back level again. But will find out next week how it works as we start out on a close to 12,000 mile trip to the west coast and back across through canada and back to florida. 694438
Review from a similar Trailair Flex in Fifth Wheel King Pin
I wasn’t expecting a big difference in the ride of my F350 and my 5er and boy was I surprised! The chucking was reduced significantly and the RV was floating on air. Figuratively and literally. It could not compensate for crappy roads and pot holes but it sure made a difference in the ride overall. 668004
Review from a similar Trailair Flex in Fifth Wheel King Pin
helps with eliminating bounce and push 660290
Review from a similar Trailair Flex in Fifth Wheel King Pin
I have used my Flex Air for over one year and put around 3000 miles on it. I purchased this for one reason to reduce bucking when I it bumps in the road. I can safely say that it has virtually eliminated the bucking. It has also made the ride a lot smoother. I would highly recommend the Flex air. I did my own install of this product by my self. My rig 2018 Toyota Tundra with a Husky 16 KW Hitch 2017 KZ Durango 30 ft. 637982
Review from a similar Trailair Flex in Fifth Wheel King Pin
Love this product 625338
Review from a similar Trailair Flex in Fifth Wheel King Pin
Install went pretty smooth. Did it from the bed of the truck, using a motorcycle jack in front and a small hydraulic in back. Make sure your torque wrench can dial to 160 ftlbs. I will update after I tow it!!! 602475
James J - 02/05/2020Review from a similar Trailair Flex in Fifth Wheel King Pin
After getting past the shipping companies mess ups, finally installed the new pin box with the help of a few friends. Had to bring toyhauler to dealer yesterday and the difference in the ride was amazing. We are not known for exceptionally smooth transitions on bridges but this hitch took the jarring out of the ride. 582788
Review from a similar Trailair Flex in Fifth Wheel King Pin
Having owned a previous version of this king pin I know and understand how it works and is why I replaced it with a similar product. The previous version was the tri-glide model that was know for going bad, which mine did. I’ve been happy with this newer version other than it seems to loose air over time. 577488
Review from a similar Trailair Flex in Fifth Wheel King Pin
The product that I ordered was what I received the person I talked to was very noligable and helpful Thanks 572652
Review from a similar Trailair Flex in Fifth Wheel King Pin
4 stars as I have just recently installed this although I received it over a year ago. I just put 750 miles on it and experienced almost every PAVED road condition imaginable and it worked great. I can't imagine what that would have been like with the stock pin box. 4 stars because I still need to see how it performs off road and I am just a few days into using it on a trip covering OR, ID, MT and WY so I still have my personal evaluation to complete and need more drive time to see if anything fails on it. Installation was a breeze but it's a heavy hitch so caution is advised. 572537
Arman K - 10/08/2019Info for this part was:
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