VCOIL Plug Gauge (GO) - Metric (STI) - Heli Coil Gauge - Right Hand - 4H - M40 x 3Helicoil gauges are manufactured and assessed in accordance with the relevant ANSI standards, specifically those defined by the American National Standards Institute ASME thread system. The GO thread plug gauge must screw into the thread cut into a part by hand (without using excessive force). If unable to do so, the thread does not meet the requested standards (=scrap). The reference temperature for parts and gauges is 20 Celsius. As a manufacturer,