Rex-Cut Abrasives 730000 Sigma Green Grinding Wheel, 36 Grit, 4-1/2in Dia. x 7/8 Arbor (Pack of 25). Sigma Green is an aggressive grinding wheel with noticeably quiet and smooth grinding action. It is the perfect balance of fast grinding, low vibration, and superior finish. The layered grain construction, coarse grain followed by a second layer of finer grain, gives this wheel the advantage of fast grinding with a superior finish. Benefits: High performance zirconium and aluminum oxide grain combination, fast stock removal, superior finish, grinds smooth and quiet, minimizes operator fatigue, controlled grinding, cool cutting, won't discolor or warp stainless steel, reduces labor rates. Applications: General fabrication, shipbuilding, tank fabrication, power plant maintenance and repair, refinery maintenance and repair. Use with Angle Grinder. 4-1/2" Diameter x 7/8" Arbor, 13, 300 Max RPM.