It is a NUPROL Bocca Viper Suppressor, and it looks awesome attached to the muzzle of my HellBoy M4!!!
After firing a few dozen rounds through my HellBoy M4, I am pretty sure that the discharge sound is louder with this foam lined faux suppressor attached to the muzzle than without it?
Perhaps, since it is made for .24cal/6mm airsoft barrels, and this is a .177cal/4.5mm steel BB barrel, it may act like an amplifier instead of a suppressor.
I didn't buy it to suppress sound, I bought it to make my HellBoy M4 look extra cool!
Now I just need to fix the charging handle spring and my HellBoy M4 will be fully functional again, even if the charging handle is just a cosmetic component.
