2BK45 1" Cast Iron Sheave Pulley for V-belt Size B, 5L 2 Grooves OD : 4.25" ID: 1" Pulley 2BK451 Outside diameter:4.25" inch Inside Diameter: 1" Inch Length through bore: 1.1563" inch Belt section size: 5L , B, BX Material : Cast Iron Belt Top Width: 5/8" 2 Grooves Keyway: 1/4" × 1/8" B-Section Groove 1 Outside Dia. 4.25" Inch Bushing H 2BK-H bushing V-Belt sheaves ( pulleys ) is an excellent choice for inch and metric shafts 2BK Sheaves are accurately machined from fine grained cast iron, statically balanced The belt series most common for this pulley is 5L, or B, BX, V-Belts.Keyway not included