10mm Lead RingLead 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.Features: Center Hole: 10mm (7/16") Outer groove width: 6mm (1/4")