The Rob Allen Gun Cassette with Loading Butt is manufactured with the same sturdy and dependable durability that you expect from all Rob Allen products. This product was designed to be easily removed and replaced by the spearo without the requirement for a diving centre visit. The Rob Allen Gun Cassette w Loading Butt has been constructed from glass filled Nylon construction. Replacement is a simple and quick operation. Simply remove your old Rob Allen Gun Cassette, slide out the stainless steel cotter pin which holds it in place, slip out the old cassette, slot in position your new cassette, push the stainless steel pin back in place and you're done.