Forged from the finest special carbon steel, carefully hardened, with polished barrel. The hole tapers back from the cutting edge so that the punchings clear freely and require only a light blow with a mallet to cut with ease. Hole diameter:3/8 In, Size 11. These punches should be used on an Osborne No. 603 Cutting pad. The use of an Osborne wooden mallet or rawhide hammer is recommended. Steel hammers are not recommended. CUTTING PAD AND MALLET/HAMMER NOT INCLUDED .