"Lewis" pattern, crest of thread, main cutting edge and taper tap in premium quality. Version with stepped head and hexagonal shank from Ø 8mm, For drilling deep holes in soft wood and European hard wood with power drill and joinery machine. < Ø 24 mm can also be used with cordless screw driver. Due to the precise production of the auger bits, they can also be used for drilling exact holes for stud bolts. For hard wood we recommend our profi product line 1493. Alloyed tool steel. 500 - 2800 rpm. e.g. Ø 12 mm 2000 rpm in soft wood.