Single block with ball bearing sheave. Allows for lashing in tight locations. Delrin(tm) ball bearing sheave ensures low-friction operation. Sheave Dia. 1 7/16", Thickness 3/4" (19mm), Width 1 9/16" (40mm), Length 2 7/8" (73mm), SWL 1000 lbs (410 kg), Weight 1.7oz (48g) Max Line 7/16" (11mm)