Low-friction carbo air blocks are lightweight, strong, reliable and affordable. Companions to the popular Harken black magic block line, these small, compact blocks have very high working loads for safe, easy trimming. Specifications Sheave diameter: 2 1/4" (57 mm) Maximum line diameter: 3/8" (10 mm) Maximum working load: 792 lb (359 kg) Breaking load: 2380 lb (1079 kg) Length: 3 5/8" (92 mm) Weight: 2.4 oz. (68 g)