The Norton 2KND7 Non-Woven Depressed Center Grinding Wheel is a 7 inch diameter by 1/2 inch thick grinding wheel with a depressed center. It has a type 27 depressed center grinding wheel shape and is made of non-woven abrasive material. This grinding wheel has an aluminum oxide abrasive and is rated for a maximum safe speed of 6,600 RPM. It can be used for general purpose grinding, sharpening and surface conditioning applications on materials like steel, stainless steel, cast iron and non-ferrous metals. This is a high quality, durable grinding wheel made in the USA by Norton, a leading abrasives manufacturer.