When loaded in the gun, the Rob Allen Semi Closed Muzzle is the end of the speargun that retains and supports the spear. 
When put into the mechanism, this muzzle holds the spear in position and serves as a guide for it when shooting. 
It has a low profile, allowing for greater maneuverability in the water when turning. 

The Rob Allen semi-closed muzzle accepts twin rubbers for increased power and has a d-shackle attachment point for mounting a reel. 
This muzzle is made of 30% glass reinforced nylon and will stand the test of time.