Single block with aluminum cheeks and ball bearing sheave. Delrin(tm) ball bearing sheave provides a low-friction yet high safe working load block. Swivel head may be locked in place to eliminate twists. Sheave Dia. 2 3/8" (60mm), Thickness 1 3/32" (28mm), Width 2 1/2" (64mm), Length 5 1/32" (128mm), SWL 1700 lbs. (771kg), Weight 10.2oz (289g), Max Line 1/2" (13mm)