The 5/16" (8mm) to 6mm adapter allows users to utilize Sea Stinger tips, or an other device with a 6mm female, on 5/16" threaded shafts. The adapter is machined out of a marine grade stainless steel for excellent corrosion resistance, and provides a long-socket overlap on the spear shaft for maximum strength. Our hex-body design allows for easy and secure installation using a wrench, eliminating the inevitable galling that occurs when using pliers to secure typical, round-body adapters. When installed with the aid of a thread-locking compound, the adapter will never loosen, giving you peace-of-mind knowing your Sea Stinger, Powerhead, or other device will stay attached to your spear shaft.