... in the design and manufacture of premium diamond drilling tools for the world engineering: geotechnical exploration, Mining exploration, Oil exploration ... tool: hoisting plug water swivel overshot outer tube & inner tube wrench foot clamp etc5. P- Gauge Core Bits: PQ, PQ3, ... 130, φ160, φ170, φ219, φ27514. Chinese Standard Metric Core Bits for Double Tube Core Barrels: φ56, φ59, φ75, φ9115. Chinese ...