Double sheave block with anodized aluminum cheeks. Works with 504-35, 504-75, 504-76 for a 4:1 purchase. Delrin(tm) sheaves ensure smooth operation and high safe working load. Swivel head may be locked in place to avoid twist. Sheave Dia. 2" (51mm), Thickness 1 21/32" (42mm), Width 2 1/8" (54mm), Length 5 1/16" (129mm), SWL 1750 lbs. (795kg), Weight 8.3oz. (235g), Max Line 7/16" (11mm)