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Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter Up to 15% Off w/ Free Shipping — 2 models

Special offer available for this product. Click here to see!
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
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Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
2 of 4 images
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
3 of 4 images
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L
4 of 4 images
Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L

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Questions & Answers
What makes this incompatible with Armaspec Silent Capture?

An extension plug goes into the BCG. The plug would keep the BCG from cycling because the rod on the silent capture would have nowhere to go since it normally gets pushed into the back opening of the BCG as it cycles.

by Steve, Verified Owner, February 11, 2025
See 1 More Answer
I want the one that folds away from the ejection port, which one should I order?

It goes off of as if you were holding the rifle. Left fold is what you'd want.

by Steve, Verified Owner, February 11, 2025
View All Q&A You Have a Question? Ask!
Customer Reviews
Helpful Positive Review
Adds 1.1 ounces to the BCG by Dan, Verified Owner, July 23, 2025
Folding is not the issue, there is an aluminum bolt extension included with this stock adapter that adds 1.1 ounces to the BCG which is no big deal if shooting supersonic rounds but may affect the cycling with pistol length gas systems shooting 300 b...
Read More...
3/3 found this helpful
Helpful Positive Review
best version yet by pr, Verified Owner, November 26, 2023
Installation now is super simple. I have both law tactical folders and previous generation sylvian folders. I believe gen 4 sylvian now surpasses all of them. Definitely a great mod to ar. Just makes sense. More rifkes should come out of manu...
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13/13 found this helpful
Helpful Positive Review
amazing and sinple to install by Wolf, Verified Owner, February 20, 2025
I installed this on my birgade BM-9. It was an easy install. You will need to remove the bolt weight for it to work properly. I highly recommend this product
2/2 found this helpful
Helpful Positive Review
Straightforward Installation and Good Value by LiamRey, Verified Owner, March 4, 2025
I’m pretty new to upgrading my AR, but installing the Sylvan Arms AR-15 Gen 4 Folding Stock Adapter was way easier than I expected. It only took a few minutes, and I didn’t need any special tools or gunsmithing skills. I looked at other folding stock...
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2/2 found this helpful
Helpful Positive Review
Sylvan gen4 stock by Northwoods, Verified Owner, October 11, 2024
Thing works great! Thought about a law tactical but couldn't just the cost on my 8.6 blackout build. Easy install and an ar10 aero lower and works seemlessly with the ar10 bolt. Highly recommend in general, but especially for the price.
2/2 found this helpful
Helpful Positive Review
Folding stock adapter by sylvan arms by ghettyup, Verified Owner, October 28, 2024
Glad I made this purchase. If you’re stuck between this folding stock adapter and the other guys, go ahead and give it a try you won’t be disappointed. I was very hesitant at first but glad I pulled the trigger ( no pun intended) . Great product at a...
Read More...
2/2 found this helpful
Read All 68 Reviews
In Stock
2 Models Available
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Product Info for Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter

The Sylvan Arms Folding Stock Adapter allows you to fold your stock and significantly reduce the length of your rifle for easy stow and travel.image

The Gen 4 AR Folding Adapter sits closer to your AR lower to reduce the length and any gaps. Turn your rifle into a foldable AR providing a compact rifle setup.

The direction of the fold is orientated to the direction as if your build was pointed down range. On a standard build, Folding to the RIGHT folds toward the ejection port. Folding to the LEFT folds off to the side with out the ejection port. Our previous folders have folded off to the LEFT.

  • Fit: Platforms .223/5.56 to .308 & Most 9mm
  • Does NOT work with Tippmann 22 or LWRC Pistols
  • Some 9mm bolt carriers with standard sizing, 5/8 ID (.625) can use the included bolt extension after removing the pin and weight from the back of the BCG
  • Compatible with your 300 Blackout AR’s for an effortless 300 Blackout Folding Stock Setup
  • If your bolt carrier group is causing the bolt extension to come up short contact us for a conversion. 
  • Includes all items needed to install.

Specifications for Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter:

Manufacturer: Sylvan Arms
Condition: New
Color: Black
Gun Make: AR Platform
Gun Model: AR-9, AR-10, AR-15
Gun Type: Rifle, Pistol
Fabric/Material: 7075 Aluminum
Threads per Inch: 1-3/16x16
Weight: 6 oz

Features of Sylvan Arms AR15 Gen 4 Folding Stock Adapter

  • Now Available as a left or right fold, pick the best AR side folder setup to fit your needs.
  • Compatible with most AR15
  • Standard 1-3/16 x 16 thread and does not require any additional parts to be used with standard AR15 Bolt Carrier Groups.
  • CNC-machined from 7075 Billet Aluminum, making it uniquely lightweight and corrosion-resistant. This assembly weighs only 6.0 ounces.
  • The included wrench makes for a quick and easy install. The product does not need to be disassembled in order to install it onto your rifle/pistol.
  • Simply screw on, fold and carry!

Package Contents:

  • Sylvan Arms AR15 Gen 4 Folding Stock Adapter
  • .625 Aluminum Bolt Extension
  • Castle nut wrench

What firearm models does the manufacturer say Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter is compatible with?

The manufacturer says that Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter is compatible with AR-15, AR-10, AR-9

Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter Orderable Models

List of Orderable Models

  • Sylvan Arms AR15 & AR9 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L , MPN: ARH400-L , UPC: 811313033353 , Code: 46S-STA-FSTA-ARH400-L
  • Sylvan Arms AR15 & AR9 Folding Stock Adapter, Gen 4, Right Fold, Black, ARH400-R , MPN: ARH400-R , UPC: 811313033360 , Code: 46S-STA-FSTA-ARH400-R

Sylvan Arms AR15 & AR9 Gen 4 Folding Stock Adapter Unavailable & Discontinued Models

List of Unorderable Models

  • USED, Sylvan Arms AR15 & AR9 Folding Stock Adapter, Gen 4, Right Fold, Black, ARH400-R , MPN: ARH400-R-EDEMO , Code: 46S-STA-FSTA-ARH400-R-EDEMO-IN-C
  • DEMO, Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Right Fold, Black, ARH400-R , MPN: ARH400-R-DEMO , Code: 46S-STA-FSTA-ARH400-R-DEMO
  • USED, Sylvan Arms AR15 & AR9 Folding Stock Adapter, Gen 4, Right Fold, Black, ARH400-R , MPN: ARH400-R-EDEMO , Code: 46S-STA-FSTA-ARH400-R-EDEMO-OB-A
  • USED Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Right Fold, Black, ARH400-R, EDEMO1, Used, Condition Fair , MPN: ARH400-R-EDEMO1 , Code: 46S-STA-FSTA-ARH400-R-EDEMO1
  • USED Sylvan Arms AR15 Folding Stock Adapter, Gen 4, Left Fold, Black, ARH400-L, EDEMO1, Condition Fair, Other , MPN: ARH400-L-EDEMO1 , Code: 46S-STA-FSTA-ARH400-L-EDEMO-OT-D
  • USED, Sylvan Arms AR15 & AR9 Folding Stock Adapter, Gen 4, Right Fold, Black, ARH400-R , MPN: ARH400-R-EDEMO , Code: 46S-STA-FSTA-ARH400-R-EDEMO-DF-F
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