Single block with aluminum cheeks. Delrin(tm) sheave ensures smooth operation and a high safe working load. Swivel head may be locked in place to eliminate twisting. 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 7.4oz (210g), Max Line size 1/2" (13mm)