Half-Moon Mast Base/Hinged/Alum. 32-15-UCHalf Moon hinged base block. Heavy duty Stainless Steel cage and base ensure reliability. SS Springs keep block upright. Aluminum UC sheave features nomex(tm) Teflon(tm) bearing and Delrin(tm) ball bearings for a low friction high strength sheave. Sheave Dia. 2 3 8" (60 mm), Max Line 5 8" (16 mm), Length 4" (102 mm), Width 1 3 4" (44 mm), Height 4" (102 mm), Bearing Height 1 5 8" (41 mm), Fasteners (4), 1 4" RH (6 mm), C C 3" (76 mm), SWL 3000 lbs.