This is a Hera USA Compensator known as the Linear Comp chambered in 223 Remington, model 11-04-09.
.223 / 5.56 (max. 7.62mm) Linear Compensator for use on short barreled rifles. The inside design with 12 separate expansion chambers leads blast and noise straight forward to increase shooting comfort and reduce noise at the shooters ears. Generation 2 with 30% less weight and a reduced outside diameter for perfect fit under Hera IRS handguard systems.
Features:
42CroMo4 construction
Black finish
30% less weight than the first generation