Sheave: Steel or Aluminum. Steel comes in Black; Aluminum comes in Red. Part Number: RP114 (Black), RP115 (Red)|Weight: 0.65 lbs (Black), 0.45 lbs (Red)|MBS: 7,500 lbs (33kN)|Rope Capacity: 1/2"|Side Plates: Anodized Aluminum|Mechanics: Bushing|Sheave: 2" Steel (Black), 2" Aluminum (Red)|Axle: Zinc Plated Steel|Size (in): 5x2.5