I started a construction apprenticeship in 1977. This grinder is AC or DC. It will handle 7 inch 9 in or 11 inch grinding wheels! It is the most heavy duty Grinder I have ever used in my 40 years of construction! If you have thick metal that you need to shape up or a bevel to grind on thick metal so you can weld this grinder is they must have! It is not for the faint of heart! Before you start you better tuck in all your clothes have a good face shield and ear plugs! There is no end to the torque and the power this grinder has!