Fiddle block with becket and adjustable cam cleat. Works with 504-45 for a 4:1 purchase. Delrin(tm) ball bearing sheaves ensure smooth operation and high safe working load. Adjustable cam cleat bracket allows you to achieve the correct angle for proper cam engagement. Lower Sheave Dia. 2" (51mm), Upper sheave diameter 1-7/16" (37mm), Thickness 2 5/16" (58mm), Width 4 1/8" (105mm), Length 7 3/16" (183mm), SWL 1750 lbs. (795kg), Weight 13.6oz. (386g),