Set of professional bimetal holesaws for drilling holes in metal, sheet metal, shapes and pipes Also perfect for drilling in plastics, furniture boards, structural sandwich panels and resins. • Recommended for professional use in industry, service and workshops The holes are made of the highest quality materials - HSS M 3 high speed steel teeth. • progressive tooth profile enhances aggressive cutting The set comes with a variable tooth pitch of 4-6 TPI (TPI - the number of teeth per inch, or 25. 4 mm), which is excellent for increasing the efficiency of the work The set comes with a variable tooth pitch of 4-6 TPI (TPI - the number of teeth per 1 inch, or 25. 4 mm).