The sheave are made of aluminum alloy mounted on ball bearings. The groove is lined by Rubber Ring. The frame are made of Mild steel. Technical Specification: Frame: Mild Steel Motion: Ball Bearing. Coating: Epoxy primer and thereafter enamel painted. Sheave dimension for 300mm (Outside diameter x root diameter x sheave width) 300 x 236 x 65 mm Safe working load for 300mm: 2.5 Ton Weight for 300mm - 10 Kg. Sheave dimension for 400mm (Outside diameter x root diameter x sheave width) 400 x 295 x 75 mm Safe working load for 400mm: 2.5 Ton Weight for 400mm - 14 Kg.