This carbide set of end mills comes in a screwed plastic case. Being carbide, they last longer than standard high speed steel (HSS) cutters and produce an excellent finish. Carbide cutters like to be worked hard and, depending on the material, coolant is essential for quality of cut and life of cutter. The set contains 3, 4, 5, 6, 8 and 10mm cutters. Please note: these cutters are designed to be held in an ER collet system. Tolerances to DIN7160 and 7161.