Premium quality stainless steel threaded speargun adapters, made in the USA. At one end is 7mm male thread to fit into 7mm (M7) threaded heads and at the other end is 6mm female thread for fitting to spear shafts with a 6mm threaded end. Fitting is 40mm in total length, but will add 25mm when threaded between your head and shaft.
Note: this adapter is made from quality 316 stainless steel - not tempered hardened stainless steel like many spears and heads. So please consider this when choosing to add an adapter in your set-up. This is not designed to be used as an extension segment for a spear, simply a means of adapting a thread size.