For those of us who want genuine imperial sized augers and not to compromise with approximate or near-enough alternatives. Designed for use in most hand power drills, the shafts are machined with six flats on to avoid any chance of slipping. Flute length is 140mm(5.1/2") and the flat sizes vary depending on the auger diameter. Auger shank sizes vary but will fit any good quality drill chuck of 13mm capacity. The 7 piece set comprises: 1/4", 3/8", 1/2", 5/8", 3/4", 7/8" and 1".