2 offset grooved main cutting edges and the serrated, longitudinally grooved pre-cutters require significantly less feed force and minimize friction and the resulting heat development, with lateral clamping screw for fixing on FAMAG auger bit shanks, for attaching to FAMAG auger bits with shank ø 13 mm, drilling and countersinking in one operation, recommended for softwood, can be used universally on all FAMAG auger bits with shank ø 13 mm