For drilling large-diameter holes in thin material or for expanding pre-cut holes , Size 4 , Dimension: 26-40mm Cone R260 K21 ND FG Disc Allroad Step Drill Bit Alpen 72102640100 Conecut Size 4 26-40mm Cone Cutter Drill Bit Shop Henry Schein Dental for Alpen R813C014FG Diamond Bur. Browse our full selection of products and order online For drilling without burr or chatter marks and widening holes (without piloting) in non-rusting sheet and soft materials. Alpen MultiCut 72901400100 Hårdmetal Multibor 14 mm Range of application: For drilling large-diameter holes in thin material or for expanding pre-cut holes.