TheUndersee Mako Headsuits a wide variety of spearguns so having one as a spare is a great idea. Made from stainless steel with an oversizedflopper and with a rounded tip for optimal fish penetration this tip is a fantastic product. It is a 5/16 thread that suits all5/16 spear tips. Being able to be threaded on and off of the spear means that you can take it off to clean and sharpen if you hit rocks.