Aluminum fiddle block with front side shackle. Works with 303-85 or 303-53 for a 4:1 system. Sheave Dia. 1 7/16", Thickness 1 7/16" (37mm), Width 1 9/16" (40mm), Length 5 3/8" (137mm), SWL 1000 lbs (410 kg), Weight 3.3oz. (94g), Max Line 7/16" (11mm)