This is the JBL #786 5/16 or 785 3/8 Spring Slide Ring for Magnum & Woody Spearguns Features: JBL 5/16 (8 mm) Spring Slide Ring or JBL 3/8" Spring Slide Ring Fits JBL4D20, 4D22, 4D24, 4D33, 4D38, 4D44, 4D45, 4D46H, 4D49, 6W Spear Guns 17-4 Spring Stainless Steel Diameter: 5/16" (8 mm) Attaches Spear Shaft to Gun and Shock Line Prevent Loss of Spear Shaft Adds Shock Absorption Keeping spare parts for your spear gun can save your trip. This 5/16" (8 mm) spring slide ring has an eyelet to thread and attach your shock line and slides over the diameter of your spear shaft. The slide ring is made for all JBL Spear Guns with 5/16" (8 mm) spear shafts. Note: 4D46T, & TC Spear Gun shaft (Front Portion) for Improved Accuracy use with JBL786H Slide Bushing. "