RIDGID 4-1/2 in. metal grinding wheels come in a 5-pack. They are made to be used on ferrous materials with a right angle grinder. Each wheel has dimensions of 4-1/2 in. x 1/4 in. x 7/8 in. (115 mm x 6,35 mm x 22 mm) and designed with a type 27-depressed center. These wheels are constructed using aluminum oxide and are tailor-made for a wide range of metal grinding tasks such as general repairs and metal fabrication.