Faithfull General Purpose Grinding Wheel 150 x 20mm Fine AloxThe 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. 125mm wheels have a bore size of 19. 05mm and are supplied with a 12. 7mm reducing bush. 150 and 200mm wheels are supplied with bore reducing bushes and will fit bench grinders with the following shaft sizes: 31. 75mm, 25. 4mm, 19. 05mm, 15. 88mm and 12. 77mm Wheel Size: 150mm x 20mm x 31.