This standard specifies the material, surface hardness and roughness, nominal diameter of metric series, diameter tolerance, diameter detection method, marking and packaging of threaded pitch gauge needles. This standard applies to common threads (M), unified threads (UN), 55° pipe threads (G, R), 60° sealing pipe threads (NPT, NPSC, NPTF) and trapezoidal threads with a lead angle of less than 5° and standard pitches Thread (Tr) pitch diameter measurement. Measuring needles are mainly used for pitch diameter calibration of threaded plug gauges. Note: Refer to GB/T28703 or GB/T32534 for thread pitch diameter measurement method.