$229.95 - $339.95
Calculated at Checkout
  • Modular design for individual personalization
  • MPX - Uses our 7.75" extension for a 13-3/8" Length-of-pull (LOP)
  • MCX/Rattler - Uses our 7.75" extension for a 13-3/16" Length-of-pull (LOP)
  • Offset extension mounts in 4 different configurations
  • Extension arms have M-LOK slots, allowing a QD sling mount anywhere along the extension
  • Positively locks in both the open and folded position
  • 6061 and 7075 construction with Type II low gloss anodized finish
  • Can be configured for the A3 Tactical Steady-brace or Tailhook brace

The A3 Tactical Modular Folding Brace (MFB) compliments the SIG MCX/MPX platform well. The MFB is designed to provide modularity in style, form, and function.  Various configurations are available to personalize the setup, and the modular system components can easily be configured to suit each users unique preferences. With multiple brace options, 2 different extension arms, and the ability to fold right or left, the user has 40 possible variations that can be configured by simply removing a few screws and changing up the configuration.

HINGE:The proven Sig hinge (provided) utilizes a positive spring-lock for both the open and closed position, allowing the user to quickly release the brace from either position.

We modify the hinge with an adapter that allows the use of our modular line of extensions.


EXTENSION ARMS: Our extension arms are available in both straight or offset configurations. Straight extensions simply extend rearward, positioning the brace end in line with the hinge point. Offset extensions offset one end 1.25" from center. Each end is symmetrical, allowing the user to mount it in 4 different positions. These offsets can be used to clear objects such as an ejection port or charging handle, raise/lower a cheek weld for different height optics, or position the brace end higher or lower to suit your shooting preference. 


All extension arms incorporate M-LOK slots along the full length of the arm. This allows the user to mount a QD (Quick-disconnect) sling mount anywhere on the extension, or any other M-LOK accessory.

BRACE OPTIONS:With our modular design, the user has their choice of A3 Tactical Steady-brace (in Polymer or Aluminum), or the Gearhead Works Tailhook (MOD1 or MOD1C). 

CHEEK RESTS: We have 2 different cheek rests available for the SIG folders - the clamp-on, non-adjustable cheek rest, or our XENO Modular cheek rest. The clamp-on is a fixed-height polymer rest measuring 4" long that raises the cheek rest 1/2". The Xeno Modular Rest can raise the cheek rest 5/8", 7/8", or 1-1/8". The XENO mounts via M-LOK and also has an offset that allows the cheek rest to be positioned 1" offset of the mount, if necessary. The XENO has an aluminum mount with injection-molded Polymer spacers and cheek rest.


NOTE: This Modular folder uses the OE Sig hinge. Due to the small offset of the Sig hinge the brace rests against the side of the firearm when folded.

NFA BRACE DISCLAIMER: The A3 Modular Brace is not designed nor should it be used as a stock or to discharge a firearm from the shoulder. The A3 Modular Brace is to be used as a pistol stabilizing arm brace. You are responsible for the proper and legal use of the A3 Modular Brace at all times. If you have purchased an A3 Modular Brace and wish to utilize the modularity function with parts designed for our Modular Stock, please be aware of all federal, state and local laws and ordinances that you must obey. The National Firearms Act regulates items such as short barreled rifles, and by utilizing components of the A3 Tactical Modular Brace as a firearm stock, you may be subjecting your firearm and yourself to NFA laws and regulations. It is your responsibility to obey all laws and properly register any NFA items you may create with use of A3 Tactical products.


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