ZERO flash. Nada. None. Designed specifically for .30 caliber (and 7.62 too, of course...) weapons with a 5/8x24 tpi muzzle thread the MA-6458 Eclipse Flash Hider does not just reduce flash, but rather eats it up entirely leaving nothing but inky, black night when shooting. Manufactured from 8620 steel, heat treated, and then coated in black oxide to create the most durable part possible, the Eclipse is the most effective flash hider currently available for the AR-10, or any other weapon that fires the 7.62 NATO round. Even better, it can be used on .300 Blackout and 7.62x39 AR-15's and SIG 556's! The Eclipse Flash Hider is marked "MA" and "0.30" to denote that it is made right here in the USA by Manticore Arms for 0.30 caliber weapons and comes with a crush washer. It is 2.25" long, weighs 3.6 ounces, and is a standard 22mm diameter allowing for the use of most standard NATO muzzle accessories.