Goodson valve seat wheels are built to grind accurately and outlast the competition. We use brass bushing to resist galling or seizing to the holder. Heat-cured, permanent expoxy bonding prevents loose bushings. Our bushings are deep set to expose the most abrasive for long life. Each wheel is pre-trued and checked to assure accurate, vibration-free grinding. General Purpose stones are used to remove material from cast-iron seats or inserts. Ideal for antiques. 11/16" x 16 thread.