... 8-16" two types. Taper Measuring Instruments for External Thread:This series products are high accuracy instruments for Petro lines ... ,mainly used to measure taper for API 5B external pipe thread, reasonable design, rigid body, high accuracy indicator ... :<=10", Indicator: 0-0.5", Resolution: 0.001"8-16", indicator: 0-0.5", Resolution: 0.001"Or, ... time! Taper Measuring Instruments for API External Thread