These blocks have nylon shells and sheaves. Loose, swivel hook with latch “G”. Plated straps and connections. All fittings are drop forged. Rope diameter: 3/8″- 1/2″. Sheave size: 2″. Rim: 5/8″. Center pin diameter: 3/8″. Weight: Single- 7 oz., Double- 12 oz. Working load is 500 lbs for single and 1000 lbs for double.