Picasso top quality, slim-line stainless steel threaded speargun adapters. At one end is 6mm male thread to fit into 6mm threaded heads and at the other end is 7mm female thread for fitting to spear shafts with a 7mm threaded end.
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.