Masterdrive single groove 3.15" cast iron pulley/sheave with 1-3/8" H bushing for B section belt is a high-quality 2-piece pulley that measures 3.15" outside diameter and is designed to be used with an H style bushing. This bushing inserts into the center of the pulley and slides over the shaft, as you tighten down the bolts on the H bushing it will tighten down on the shaft. This style of pulley is much more secure than a standard single-piece pulley. The bushing is made of solid steel and precision machined to ensure high quality and secure attachment to your motor/engine shaft. This pulley accepts B Section also known as 5L series belts and is 1/2" wide. Specifications: Solid Steel Bushing Single Groove Pulley 1-3/8" Bushing Included For Use on 1-3/8" Shaft Outside Diameter of Pulley: 3.15" High-Quality Cast Iron Construction Accepts: B Section / 5L Section Belts