Hougen® Annular Cutter, Imperial, series: 535M, 1 in Cutter dia, 1 in Cutting Depth, 3/4 in Shank, Double Flat Shank, M2 HSS Cutting Edge, M2 HSS. Hougen® 12320 12000 Imperial Annular Cutter, 1 in dia Cutter, 1 in D Cutting, M2 HSS, Double Flat Shank