This sprocket is machined to accept a JA Bushing ANSI 40 Chain JA Bushing Sprocket Outside Diameter: 3.30" Number of Teeth: 19 JA Bushings are Sold Separately Here. https://www.voodoosprockets.com/product-category/quick-detachable-qd/ja-qd-bushings/ ANSI 40 Chain QD Sprockets are designed for use with ANSI #40 roller chain, providing efficient power transmission in industrial and mechanical applications. These sprockets feature a Quick Detachable (QD) bushing system, allowing for easy installation, removal, and secure mounting on shafts of various diameters. Typically made from high-quality steel for durability and wear resistance, ANSI 40 QD sprockets come in a range of tooth counts (pitch diameters) to suit different speed and torque requirements. They are commonly used in conveyors, agricultural machinery, and power transmission systems, offering precision-machined teeth for optimal chain engagement and minimal wear.