Surgical Acorn burs can be used in a variety of surgeries where conical shaping is required. Acorn burs are different from round burs in that they have a conical tip for pinpoint cutting and shaping. Omega?s Acorn burs are made from medical grade stainless steel. The standard length of the A4070 bur is 70mm straight shaft with a head size of 4.0mm. 8 flutes on the Acorn head help remove excess material smoothly and efficiently. All our burs are manufactured right here in the United States.