Yugo grenade launcher attachment/spigot. It blued steel, most are unissued and coated in cosmoline, however, some have finish wear and light surface rust. They screw onto barrels with 14x1LH threads. If you can find grenade launcher blanks and practice grenade, they are a blast, but still fun to screw around with regular blanks and random household items that fit on the spigot.
*Not for sale for CA residents. We can not ship this to CA.