Good price. well made - Yankee Hill Machine 5.56mm Crush Washer For 1/2 Inch Threads YHM-28-5C-W

It’s a crush washer. It does exactly what it supposed to do. I use them on all my barrels with muzzle devices. Yankee Hill is known for quality machining and manufacturing. This is well-made and machined. There’s not too much else love to say. Looks good, feels good and does exactly what it supposed to do.