38 Special / .357 Magnum Ultralite is our most popular unit, designed to be used on a speargun shaft or a personal protection device mounted on our 26" Rod & Ball Assy. many scuba divers prefer this over other devices. Hairpin Safety, 6mm Mount Thread,303 Stainless Steel. ***** Rod & Ball Asembly Sold Separately ***** POWERHEAD WEIGHT: 2.4 oz.