... in the design and manufacture of premium diamond drilling tools for the world engineering: geotechnical exploration, Mining exploration, Oil ... , B86, B101, B116, B131, B14613. Chinese Standard Metric Core Bits for Single Tube Core Barrels: φ36, φ46, φ56, φ59, φ75, φ91, ... 130, φ160, φ170, φ219, φ27514. Chinese Standard Metric Core Bits for Double Tube Core Barrels: φ56, φ59, φ75, φ9115. Chinese ...