taper button bit used for hard or very hard rock formation. ... formation. Excellent quality and durability and Specialized heat treat & stress relief,also Maximum performance and hole cleaning ability (1) Type: button ... ) Size: Size: 19mm, 22mm, 25mm(3) Diameter: 30-42mm.(4) Taper: degree 4°46′ 6°, 7°, 11°, 12°.(5) Package: in ...