... 4. Good feedback of clients 17 1/2" tricone drill bit : size from 60mm to 26 inch,metal sealed and Elastomer sealed ... Type Available Size: 6",6 1/2",7 1/2",8 1/2",9 1/2",9 5/8",9 7/8",12 ... reduces the probability of cone-dropping to minimum.Main Type AvailableSize: 8 1/2",9 1/2",9 5/8",9 7/8 ... cone which reduces the probability of cone Cdropping to minimum.Main Type AvailableSize: 2 3/8",3",3 5/8:",3 7 ...