2-3" aluminum sheaves, sealed ball bearing, and stainless steel axle. Part Number: RP155|Weight: 1.4 lbs|MBS: 13,900 lbs (61kN)|Rope Capacity: 1/2"|Side Plates: Blue Anodized Aluminum|Mechanics: Bearing|Sheave: (2) 3" Aluminum|Axle: Stainless Steel|Size (in): 7x4