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  5. 1/4 Inch - FIF
MB Sturgis Propane Adapter Fitting w/ Back Check - 1/4" Female Inverted Flare x 1/4" MPT

MB Sturgis Propane Adapter Fitting w/ Back Check - 1/4" Female Inverted Flare x 1/4" MPT

Item # 204120-MBS
Our Price: $5.63
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Propane Fittings
Shipping Weight: 0.06 lbs
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204120-MBS - 1/4 Inch - FIF MB Sturgis Adapter Fittings
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Fitting lets you connect your propane cylinder to your regulator with an inverted flare pigtail. Back-check prevents gas from leaking out of the regulator inlet. Great Prices for the best propane fittings from MB Sturgis. MB Sturgis Propane Adapter Fitting w/ Back Check - 1/4" Female Inverted Flare x 1/4" MPT part number 204120-MBS can be ordered online at or call 1-800-940-8924 for expert service.
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  • Reviews (45)
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MB Sturgis Propane Fittings - 204120-MBS

  • Adapter Fittings
  • 1/4 Inch - Male NPT
  • 1/4 Inch - FIF
  • MB Sturgis

Fitting lets you connect your propane cylinder to your regulator with an inverted flare pigtail. Back-check prevents gas from leaking out of the regulator inlet.


  • Fitting lets you connect your propane cylinder to your regulator with an inverted flare pigtail
  • Internal back-check prevents gas from leaking out of the regulator inlet
  • 1/4" Female inverted flare connects to an inverted flare pigtail
  • 1/4" Male NPT end screws into the inlet of your regulator
  • Sturdy brass construction
  • Made in the USA
  • 1-Year limited warranty

204120-MBS MB Sturgis Propane Adapter - 1/4" Male Inverted Flare x 1/4" MNPT - Back Check

Video of MB Sturgis Propane Adapter Fitting w/ Back Check - 1/4" Female Inverted Flare x 1/4" MPT

Videos are provided as a guide only. Refer to manufacturer installation instructions and specs for complete information.

Video Transcript for Review of MB Sturgis Propane - Adapter Fittings - 204120-MBS

Today we'll be taking a look at the MB Sturgis propane adapter fitting. This lets you connect your propane cylinder to your regulator with that inverted flare pigtail and it has an internal back check to prevent any gas from leaking out of the end of the regulator inlet. One of out 14 or excuse me, one of our quarter inch female inverted flare to help to connect to our pigtail and our quarter inch male NTPN to screw into the inlet on your regulator. It's made of brass. We don't have to worry about any issues with strength or corrosion. And this is made in the USA.The whole adaptor measures about 3/4 of an inch long or about 7/8 of an inch long.

The fitting is about 5/8 of an inch.And that's going to do it for our look at the MB Sturgis Propane adapter fitting with back check.

Customer Satisfaction Score:

Customer Reviews

MB Sturgis Propane Adapter Fitting w/ Back Check - 1/4" Female Inverted Flare x 1/4" MPT - 204120-MBS

Average Customer Rating:  4.8 out of 5 stars   (45 Customer Reviews)

Fitting lets you connect your propane cylinder to your regulator with an inverted flare pigtail. Back-check prevents gas from leaking out of the regulator inlet.


Used it to replaced the new pigtail that had 1/4 inverted flare end.The regulator on the camper had 1/4 fpt.It did the jod


This check valve worked great for my Elk hunting trip in January. Temps were down to -12F at night (went through a lot of propane). Auxiliary propane tank connected to main system did not reverse flow when regulator switched to main tank(s), or leak when disconnecting tank for filling.

Ronald G.


I needed a check valve for an additional hose from a tee on one side of the regulator to a bottle on the ground for extended camping. The original tee would allow gas to escape when I changed the auxiliary tank. This valve solved that problem perfectly.


I had no propane flow to my trailer the check was plugged replaced with MB Sturgis propane fitting and now I’m a happy camper

Steve L.


Still working fine and I’m still a happy camper


The part was correct and of a good quality but the shipping was terrible. It took a very long time before it ever left the shipper and it was the slowest shipping service I had ever seen. The tracking information was poor at best I don’t know what all the delays were about but I am discussed.



It is still working great after a year but just wish it would have came more promptly.


Ordered 2 Sturgis propane adaptor fittings with back checks. Received exactly what I ordered, installed on my trailers pressure regulator. Very good price for a great product!


Important to use this when running on the other tank


This check valve is standard on new systems however it may not be on older units. Easy to install and works as it should. use caution when installing to insure it functions correctly by using liquid pipe dope rather that tape.


Quality made thinymajigger :-) Used to get the correct fitting if you need it for your propane automatic switch or if you bought the wrong propane pigtails...


the propane fittings were just what I needed, and the best part was that the salesperson was able to walk me through identifying the correct pieces. Price and delivery were great, as well. 5 stars!


installed in propane line into the RV. Had to use as as line had inverted flare and regulator had pipe fitting.


etrailer is great to deal with. They always have what I need and they always ships things out very quickly. I highly recommend them for your towing and trailer needs.


Mated to existing lp gas regulator (1/4" MNPT), and received my 1/4" male inverted flare pigtails. It added the peace of mind of having an additional check in the line also.


Exactly the part we needed for ou extend a stay. No propane run out last year.


The first valve didn't make it and appears to be lost in the mail. I contacted ETrailer customer support and Lisa was great! I had the new valve only two days later.


They fit perfect an was the part we needed and a great price fast shipping. You have a new customer and will be using etrailer for items.


Replaced check valves that were clogged/poor flow.


Perfect item. Existing backflow valve seemed to be working correctly but when replaced it was obvious it was not. Simple inexpensive maintenance item.


Excellent replacement for oem.


I love etrailer


Thank you for the quick delivery of the order. Very nice service. I am very happy with this company. I recommend it to everyone. It gives five stars. Thank you .


Purchased these along with the Sturgis hoses... fine quality and performed as expected.


Good quality. Quick ship and accurate,


The part I needed, and arrived within a reasonable amount of time.



Works shipped fast

Show More Reviews

See what our Experts say about this MB Sturgis Propane Fittings

  • Are There Propane Adapters/Lines that Prevent Gas from Leaking
    Sounds like you are asking about a back check style of line/adapter. We have the part # 204120-MBS that is a propane fitting that has a back check built into it. It is a fit for 1/4 inch NPT lines and will prevent gas from leaking out of the regulator inlet. Hoses don't generally fail often, but it is possible that they can fail. It is possible your current line has a back check built into it and it has failed.
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  • Can MB Strugis 100019-36 Propane Fill Hose be Used to Connect Grill to 15 Pound LP Tank
    I spoke with my contact at MB Sturgis about supply hose # 100019-36. He stated that in order to use it with your set up you would also need an adapter # 204120-MBS to make everything work together.
    view full answer...
  • Does JR Products Automatic Changeover Regulator Include Back-Check Valve
    The JR Products automatic changeover regulator, part # 37207-31525, does have a back-check valve so you don't need to purchase the adapters separately with part # 204120-MBS. You only need to purchase the adapters if you need a replacement for any reason.
    view full answer...
  • Is Male Inverted Flare Fitting a Left Hand Thread Like the POL
    The male inverted flare fitting of part # 100019-15 that goes into a regulator is a standard right hand thread. You're correct the POL connection is a left hand but that's the only one that's unique in that sense. The inverted flare end fits into dual stage regulators that have the brass adapters like part # 204120-MBS. This way you don't need to use tape to make the connection with the hose.
    view full answer...
  • Is An Adapter Needed For Automatic Changeover RV LP Gas Regulator
    You actually do not need the adapter you mentioned # 204120-MBS, your Automatic Changeover RV LP Gas Regulator # 37207-30395 has two 1/4" inverted flare fittings that connect to your propane tanks, and has a 3/8" female NPT connection that will connect to your trailer, and use # 100040-72-MBS to connect them together.
    view full answer...
  • Availability of Pigtail Hose Without Back-Check
    We do have the MB Sturgis Sturgi-Stay Propane Fill Hose # 100019-24 which doesn't have a back-check. This pigtail has a POL fitting on one end and then a 1/4" male inverted flare on the end that connects to your regulator so if you already have an adapter in the regulator you'll need to remove it to use this pigtail. Please note that when used as part of a dual-cylinder setup, this will not be RVIA compliant. The adapter fitting # 204120-MBS would need to be purchased (which has the back-check)...
    view full answer...
  • Is a Back Check Valve Required For Connecting a Pigtail Hose to an Auto-Changeover Regulator?
    Both the MB Sturgis Propane Pigtail Hose # 100019-15 and Propane Hose # 37207-30605 will require a Adapter Fitting w/ Back Check # 204120-MBS when going into a changeover regulator. Most Regulators # 888001-MBS will come with these back check valves already in place, and as long as you do not remove it or it is not damaged you will not have to get a new fitting.
    view full answer...
  • 4 Foot Hose to Connect Propane Tank on Travel Trailer to Regulator
    We have 48 inch hoses to go from a propane tank to a regulator but your fittings don't seem to match standard sizes. A trailer normally has tanks with a Type 1 connection and the standard inlet on regulators is 1/4 inch NPT. Send me some pictures if yours seem different. A 48 inch hose that works for the standard fittings is part # 100575-48-MBS. For this hose you also need an adapter, part # 204120-MBS. Ths converts the inlet on the regulator from 1/4 inch NPT to 1/4 inch FIF. The only...
    view full answer...
  • Recommended 3'+ Propane Supply Hose for Pop-Up Camper
    If you're searching for a hose to go from the tank to the regulator then you'll need the MB Sturgis Propane Pigtail part # 100575-36-MBS for 3' long or part # 100575-48-MBS for 4' long. Please note, the pigtail hoses use an inverted flare and most regulators use national pipe taper (NPT) so if you don't already have the brass inserts you'll need them as well, the MB Sturgis Propane Adapter Fitting part # 204120-MBS.
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  • Replacement Propane Hose Needed
    I suggest that you replace with the Propane Hose with Back Check - Type 1 x 1/4" Male NPT, # 37207-30855. This hose will connect your tank with the Type 1 connector and have a 1/4 Inch - Male NPT on the other for your regulator side connection. From attached image I can see that you have female inverted flare connection. However, I cannot tell from image definitively what size. It may be a 1/4", which I suggest the Camco Propane Fitting - 1/4" Male NPT x 1/4" Female Inverted Flare, #...
    view full answer...
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  • 3' Adapter Hose For Attaching 100 Gallon Propane Tank To 3/4" Black Steel Pipe
    The MB Sturgis Propane Pigtail Hose # 100019-36 is 3' long and has the POL fitting to attach to your 100 gallon propane tank. The other end has a 1/4" male inverted flare fitting which you will be able to adapt to the 3/4" fitting on the black steel pipe. You will want to first use the MB Sturgis Propane Adapter Fitting w/ Back Check # 204120-MBS to adapt to a MPT fitting and prevent any propane in the steel lines from releasing when changing out the tank. You will finally need to source...
    view full answer...
  • Removing Two 30 lb Propane Tanks and Replacing Them With 100 lb Propane Tank
    You can remove your two 30 lb tanks and add a 100 lb tank, but you will need a number of parts, including a new regulator for a single tank. What you will need are the MB Sturgis Sturgi-Stay Propane Fill Hose - POL Pigtail x 1/4" Male Inverted Flare - 3' # 100019-36 to attach to your tank, then the MB Sturgis Horizontal 2-Stage Propane Regulator # 108221. You will need to attach the MB Sturgis Propane Adapter Fitting w/ Back Check - 1/4" Female Inverted Flare x 1/4" MPT # 204120-MBS to...
    view full answer...
  • I Need a 20 Inch Propane Tank Pigtail Hose with a Type 1 x 1/4 inch NPT Fitting
    I'm assuming you are asking for a 20 inch hose, which the closest option we have at this time would be the combination of our pigtail hose, part # 100833-24, and adapter # 204120-MBS. If you don't mind using a typical rubber hose, you can use part # 37207-30865.
    view full answer...
  • Propane Regulator for a Modine 45K BTU Hot Dawg heater
    Yes, you should go with a dual stage like the MB Sturgis 2-Stage Propane Regulator part # 108220 for vertical or part # 108221 for horizontal because it can be adjusted to a 12" water column outlet. In order to do this you will need to remove the black cap and turn the valve until the correct pressure is achieved. This will require a flow meter so if you do not have one it will be best to take it to a professional to have done. It is currently set at 11" water column outlet which the manufacturer...
    view full answer...
  • Recommended Type 1 Propane Pigtail with Dark Green Connector
    It sounds like you're looking for a Type 1 propane pigtail, which are available in 12" with part # 100833-12, 18" with part # 37207-30735 or 30" with part # 100575-30-MBS; these all have the dark green Type 1 connection that you're seeking but they do not come in a 10" long version. For the 1/4" MIF to 1/4" Female MPT adapter you can use the # 402258-MBS which does not have a back check, or the # 204120-MBS which comes with a back check. There is not a Female MPT to MIF adapter available,...
    view full answer...
  • Dual Propane LP Tank Setup 100 Lb for RV or Travel Trailer
    Yes, the # 100019-24 pigtail can be used to connect your dual-cylinder 100 lb propane setup to the regulator on your RV. Since this hose does not have a back-check to contain a gas leak, you will need the # 204120-MBS fitting that includes a back-check. Without the back-check, your setup would not be RVIA (Recreation Vehicle Industry Association) compliant. You mentioned that you'd like to connect to a T first, before connecting to the regulator. I called my contact at MB Sturgis to...
    view full answer...
    Image 1 for
  • Regulator For a 100 lb Propane Tank to a Ventless Heater
    The regulator you need is MB Sturgis part # 108220. The maximum propane flow capacity of this regulator is 400,000 BTU per hour so it can handle the 18,000 BTU of your Empire wall mount ventless heater. The two stage regulator is also the best option for the heater that is most likely running for extended amounts of time. Most likely there is a POL fitting on the tank, you can use 100019-48 pigtail to the regulator. The hose does not have a back check so you need adapter fitting part...
    view full answer...
  • Pigtails Needed to Connect Dual Propane Tanks to Regulator on Travel Trailer
    For a typical travel trailer propane setup you will have 1 of 2 pigtails. The first will have the Type 1 connector (with the green cap) and the other has a 1/4" MPT fitting like what we find on the pigtail # 100473-12. I believe this is what you currently have but I think the end you're seeing looks like the MB Sturgis Propane Adapter Fitting # 204120-MBS and I think the white plastic piece is part of the back-check. The other type of pigtail that we see has the same Type 1 connector,...
    view full answer...
  • Replacement of Propane Hose From Tank to Regulator that Leaks
    So it's the elbow piece that you need? Without knowing the fittings I can't be sure but since that should be the inlet to your regulator it probably has a 1/4 inch male fitting on the end going into the regulator and a 1/4 inch female on the other. We don't carry any 90 degree adapters with those fittings. If those are correct you can probably bypass it if you can get the hose to connect directly to the regulator. Or if I'm wrong about the fittings let me know what they are and I'll see...
    view full answer...
    Image 1 for Image 2 for Image 3 for
  • What is the Fitting Size on the Stainless Steel Furrion 2-in-1 Range Ovens
    The 21" Stainless Steel Furrion 2-in-1 Range Oven # FSRE21SABL has a 3/8” Male Flare fitting. If you are wanting to use a 20 or 30 lb propane tank with this oven then I recommend using the 4' # 100040-48-MBS, 6' # 100040-72-MBS, or 12' # 100040-144-MBS hose along with a dual stage regulator, part # 108220 with the fitting # 204120-MBS for a single tank or part # CAM59005 for dual tanks. Once you have all of this connected you just need a pigtail like part # 100833-15 to your propane tank(s)...
    view full answer...
    Image 1 for

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Info for this part was:

Employee Jeff D
Installed by:
Jeff D
Employee Kathleen M
Installed by:
Kathleen M
Employee Jameson C
Expert Research:
Jameson C
Employee Mary K
Updated by:
Mary K
Employee Wilson B
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Employee Carrie F
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Carrie F
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