... history Milled Tooth Rock Roller Bits: 7 7/8 to 14 1/2 ModelTCI BIT, STEEL TOOTH BITIADC CODE ... Clays, Sands, Salts etc.1187.3~346.17 3/8~13 5/8441~735120~50softClays, Soft Shale, Marl, Sands, Salts ... 6 7/8245-490100-50187.3~346.17 3/8-13 5/8490-78490-40Medium softShale, Marl, Sandstone, Soft Limestone ... 4-6 7/8294-53980-40187.3-215.97 3/8-8 1/2580-88260-40Very hardQuartzite, Chert, Basalt Granites, ...