These wheels do a great job cutting cured fiberglass and carbon fiber laminates. We had no problem cutting through 4 layers of carbon and 10 layers of Style 7781 fiberglass - both cured with epoxy! Although these wheels can be used for other materials in addition to composites, they should not be used on steel. Mandrel is included. Part number 1929-A is a 7/8" diameter diamond wheel with a thickness of .023" for thin, clean cuts. Part number 2304-A is a 1.25" diameter carbide wheel with a thickness of .070" for rough, aggressive cuts.