Harken Lead Rings are simple, weight-saving devices used to route line for jib in-haulers, twings, barberhaulers, lazy jacks, cascading backstays, and other applications requiring minimal fine-tune adjustments. Rings are Hard Lube-anodized 6061-T6 aluminum for a smooth, slippery surface, and with no moving parts, wear is minimal.SpecificationsCenter hole diameter: 5/16″ (8 mm)Outer groove width: 3/16″ (5 mm)Weight: 0.093 oz. (2.65 g)