This is a Magpul Industries Brace known as the BSL, model MAG1143-BLK.
The Magpul BSL is an AR arm brace designed to improve the single-handed employment of large-format pistols. The BSL utilizes Magpul design and engineering to offer a stabilizing accessory with a robust feature set and trusted Magpul quality. With classic Magpul aesthetics" the BSL is compatible with Mil-Spec carbine receiver extensions and employs a simplified" durable" and easy to use adjustment mechanism. An integrated QD cup and two M-LOK compatible slots provide ambidextrous sling mounting options and enable stabilizing sling tension to be applied" drastically increasing single-handed control of the firearm. With a straight-forward design and Magpul innovation" the BSL is a simple solution to improving your AR pistol.
Features:
IMPROVES SINGLE-ARMED USE OF LARGE-FORMAT PISTOLS
M-LOK compatible slots for additional sling mounting options
Toolless, single-handed adjustment
High-strength polymer and metal construction
