This is a Yankee Hill Machine Co Blast Diverter chambered in 556NATO, model YHM-3130.
YHM designed this QD Blast Deflector to work with multiple YHM QD muzzle devices. The QD Blast Deflector locks on just like a YHM Suppressor. The Mechanism is fast" positive and virtually impossible to disengage accidentally.
Features:
4140 Chrome moly steel
Melonite QPQ finish
Made in the USA