This is a SB Tactical Stabilizing Brace known as the FS1913, model FS1913-01-SB.
A low-profile" left side-folding strut design compatible with all platforms utilizing an M1913 interface at the rear of the receiver. The FS1913 is a complete assembly offering pull-through opening and a solid lock-up when extended. Comes with adjustable nylon strap.
Features:
Black finish
Folding pistol brace
Fits Sig MCX and MPX
Advanced steel hinge design
Pull-through design offering quick deployment
