Fiddle block with anodized aluminum cheeks, delrin(tm) ball bearing sheaves, becket and cam cleat. Works with 506-45 for 4:1 purchase. Delrin(tm) ball bearing sheaves ensure low friction and high safe working load. Fast entry cam cleat allows easy line engagement. Sheave Dia. 1-7/16" (37mm), Thickness 2 5/16" (58mm), Width 3 7/32" (82mm), Length 6 13/32" (163mm), SWL 1500 lbs. (680kg), Weight 11.6oz (329g), Max Line 7/16" (11mm)