The Faithfull Vitrified grinding wheels are suitable for use on most types of bench grinder. White wheels are ideal for the general purpose grinding of ferrous metals but they are particularly suited for the sharpening of cutting tools such as chisels and plane irons. These wheels help keep your tools cooler to avoid overheating and weakening the cutting edge. Supplied with bore reducing bushes and will fit bench grindersThe Faithfull FAIGW15020WG is a 150mm x 20mm wheel and is supplied with bore reducing bushes and will fit bench grinders with the following shaft sizes:31.75mm19.05mm15.88mm12.77mmAdditional Information:• Wheel Type: Grinding Wheel - Medium• Diameter (mm): 150• Thickness (mm): 20