Single V-Groove Pulleys Machined to exact tolerances and balanced to reduce vibration, these solid cast iron pulleys will make any power transfer system run smoother and quieter. Solid cast iron, Keyway & Setscrew, For 3L â 4L â A belts, Static balanced Pitch Diameter: 6", Bore: 5/8", Standard Keyway W x D: 3/16" x 3/32"