These are designed for reaming holes so that standard taper pins will be able to fit properly. Best results will be attained if the hole is drilled a few thousandths smaller than the small diameter of the finished reamed hole. metal: HSS M2. Straight flute and helix flute both available on request. Nom.Decimald2d1L1L2Sq. aNo.Dia.Equiv.mmmmmmmmmmofmmFlutes1.50.05911.42.1437571.8420.07871.92.8648682.242.50.09842.43.3648682.830.11812.94.0658803.1540.15753.95.266893450.19694.96.3673100560.23625.981051356.3680.3157.910.814518086100.39379.913.4175215106120.472411.81621025511.28130.511812.8616.7421025512.58140.551213.8617.7421025512.58160.629915.820.423028014200.787419.824.825031018