Review on Enhanced Performance: Flute Coated End Mill Pieces by Allan Lambert

This is a high speed steel. Not carbide. They are excellent for aluminum. I've had great results with the LMS High Torque Mini Router 3990. However, I needed steel routers, not a carbide hole saw. After I cut 30 square inches in four or five passes, my four-flute 3/4 router bit wore out and started sparking. I finished with two flutes. I've since bought a carbide cutter. I will also buy a new set because the whole set costs about the same as a carbide bur.