Single block with anodized aluminum cheeks and aluminum sheave. Aluminum sheave runs on nomex(tm)/Teflon(tm) bearing for low-friction and high strength. Swivel head may be locked in place to eliminate twist. Sheave Dia. 2 3/8" (60mm), Thickness 1 3/32" (28mm), Width 2 1/2" (64mm), Length 5 1/32" (128mm), SWL 2250 lbs. (1020kg), Weight 10.2oz (289g), Max Line 1/2" (13mm)