BK20 1/2" ID Solid Pulley - 2" OD for V-belts cast iron size 4L, 5L1 Groove Solid V Belt Pulley BK20 1 2" Bore, 2" OD Perfect for 4L & 5L Belts Heavy Duty, Solid Design This BK20 solid V belt pulley is a single groove powerhouse designed for dependable power transmission. With a 2" outer diameter and a 1 2" straight bore, its built to handle standard 4L and 5L V belts. The solid construction and hex set screws make it ideal for small motors, compressors, and light duty machinery. Outer Diameter: 2" inch Bore Size: 1