Fiddle block with swivel shackle and becket. Works with 303-45 for a 4:1 purchase. Delrin(tm) sheaves ensure low-friction and high safe working loads. Sheave Dia. 1 7/16", Thickness 3/4" (19mm), Width 1 7/8" (48mm), Length 6 7/32" (158mm), SWL 1000 lbs (410 kg), Weight 4.8oz. (136g), Max Line 7/16" (11mm)