... Material: Alloy steel Certificated by API&ISO9001:2008 New PDC Bits(12-1/4") Description about sell rock bits,tricone bits, ... compact) grades and shapes applied for rock formations as follows:1. Andesite, marble, metamorphic schist (For hard, low abrasive ... formations)Being widely used in the field of mine, transportation, tunnel and hydroelectric for shelving reticular support. Model114,117,127,437 ...