Double block with SS Cheeks. Works with 03-15 for a 3:1 purchase or 303-85 for a 4:1 purchase. Delrin(tm) sheaves ensure smooth operation and high safe working load. Sheave Dia. 1 7/16", Thickness 1 7/16" (37mm), Width 1 9/16" (40mm), Length 3 25/32" (96mm), SWL 1000 lbs (410 kg), Weight 4.1oz. (116g), Max Line 7/16" (11mm)