7/16 diameter and machined to accept traditional 3/8 diameter bore bronze or stainless steel harpoon darts. Features the patent pending L.T. Marine Dart Retention System. Fit all L.T. Marine designed and manufactured harpoons. Made from 316 Stainless Steel with 7/16-14 thread pattern. If using our dart shaft with other brand darts, please remove o-ring to prevent dart from locking onto tip of dart shaft.