Double block with front side shackle. Works with 303-33 for a 4:1 purchase or 303-15 for a 3:1 purchase. Delrin(tm) sheaves ensure smooth operation and high safe working loads. 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 3.3oz. (94g), Max Line 7/16" (12mm)