Single block with anodized aluminum cheeks and aluminum sheave. Aluminum sheave runs on nomex(tm)/Teflon(tm) bearing for exceptional strength with low-friction. Swivel head may be locked in place to avoid twist. Sheave Dia. 2" (51mm), Thickness 15/16" (24mm), Width 2 1/8" (54mm), Length 4 13/32" (112mm), SWL 1750 lbs. (795kg), Weight 6oz. (171g), Max Line 7/16" (11mm)