If you are experiencing excessive motor noise, slipping, straining, or overall poor performance of your Conventional Headstock with Gilmer Belt, it's time to upgrade to the quiet, highly-efficient Poly-V Drive System. The Poly-V Belt is a full 7/8 Inch wide with 9-ribs to grip the pulleys for full power transmission. The Poly-V Sheave has matching high-speed balanced grooves for smooth running performance. Drive Sleeve Assembly includes precision machined Poly-V Pulley with high-speed bearings and extra grooves for proper belt alignment. Double Bearing Quill Assembly is precision machined and factory-aligned with two high speed bearings for smooth operation under load. Gilmer-to-Poly-V Drive System Upgrade With Motor Includes: High-Speed, Two-Bearing Quill, Drive Sleeve Assembly, Poly-V Sheave, Poly-V Drive Belt, and easy to follow instructions.