Model Number: 8 1/2ST437GK(IADC:437) Brand Name: TRANSTONE Key Specifications/Special Features: Cutting structureThe wear-resistance of teeth is enhanced with premium tungsten carbide hard facing on the tooth surfaces for steel tooth bit. The durability of premium tungsten carbide inserts is improved with new formulas and new techniques for insert bit.Gauge structureMultiple gauge protection with gauge trimmers on the heel of cone, tungsten carbide inserts and hard facing on the shirttail increases gauge holding capability and bearing life.Bearing structureHigh precision journal bearing with two thrust faces. Balls lock the cone. Hard faced head bearing surface. Cone bearing inland with friction-reducing alloy and then silver-plated. Abrasion resistance and seizure resistance of the bearing are improved.Seal and lubricationPremium HNBR O-ring, optimal seal compression and curved seal structure can enhance the seal performance. The pressure compensator system and advanced grease can greatly increase the lubricating reliability.Product applicationIt can receive high WOB in the conventional drilling. It is suitable for various formations by matching cutting structure with different tooth exposure height. Size (in) Size (mm) IADC WOB (kN/mm) RPM (r/min) Applicable formations 8 1/2 215.9 437 0.35-0.9 150-70 Very soft formations with low compressive strength and high drillability, such as clay,mudstone,chalk, gypsum, salt, soft shale, soft limestone & more