MASTERCRAFT AIR-POWERED DIE GRINDER. This is a brand new in box die grinder. At 25000 RPM, Mastercraft Full Die Air Grinder is a lightweight and powerful full die air grinder designed for your convenience. With a comfortable and ergonomic grip, this die grinder is easy to handle, and features a rear exhaust to keep air flow away from your workspace. This die grinder by Mastercraft is perfect for a variety of tasks such as removing heavy burrs, grinding welds smooth, and performing heavy grinding. Made with durable and high quality aluminum.