1.Tungsten carbide insert bit, TCI bit, button bit 2.Sizes ... 1.Cutting Structure The durability of premium tungsten carbide insert is improved with new formulas and new techniques and new ... 2. Gauge StructureGauge protection with gauge inserts on the gauge surface of the cone, tungsten carbide inserts and hardfacing on ... , 241, 537….………..………………………………26 131, 211, 537, 517…. tungsten carbide drill bits