... external thread, Conform to API Spec 5B requirement. Range: <=10" and 8-16" two types. Taper Measuring Instruments for External Thread ... 5B external pipe thread, reasonable design, rigid body, high accuracy indicator and sensitive movement system, conform to API Spec 5B requirement.Sizes ... :<=10", Indicator: 0-0.5", Resolution: 0.001"8-16", indicator: 0-0.5", Resolution: 0. ...