Single stand up ball bearing block. Stand up spring keeps block upright when not in use. Stainless steel base spreads load out and may be used with 97-49 backing plate. (sold separately) Delrin(tm) ball bearing sheave provides a low-friction high strength sheave. Sheave Dia. 2-2/8" (60 mm), Max Line 1/2" (13 mm), Dia. includes urethane base 3-3/8" (86 mm), Height 4-25/32" (120 mm), H2 2-15/32" (63 mm), Fastener Size (4),1/4" RH (6 mm), C/C 1-11/16" (43 mm), SWL 1700 lbs (771kg), Weight Alum. 11.7 oz (332 g)