The hexagonal bit allows for quick tool changes. Ideal for chamfering, deburring and countersinking without burrs or edges in steel, cast iron, non-ferrous and light metals. The best results are obtained at low cutting speeds.Long 90° HSS chamfering end mills with 1/4″ hex shank for quick tool changes. Ideal for chamfering, deburring, and countersinking without burrs or edges in steel, cast iron, non-ferrous metals, and light alloys.