The Faithfull aluminium oxide vitrified grinding wheels are suitable for use on most types of bench grinders and are suitable for normal grinding of ferrous metals. Supplied with bore reducing bushes and will fit bench grinders with the following shaft sizes:Wheel Size: 200mm x 20mm x 31.75mmGrit: 60Bond Hardness: NM/S: 35Max R.P. M: 3,350 Faithfull General Purpose Grinding Wheel 200 X 20Mm Fine Alox in Grey