The SCHMALKALEN 3985.07 differential thread ring gauge for American tapered GAS NPTF threads according to ANSI / ASME B 1.20.3 and B 1.20.4 with Filetto G= Ø G 1"-11,5 is an inspection tool designed for fast and reliable checking of tapered external threads used on fittings, pipe connections, mechanical components, turned parts and industrial applications where the threaded connection must comply with precise geometrical limits and demanding functional requirements. Manufactured from high-quality hardened tool steel, it provides strong wear resistance, dimensional stability and an excellent contact surface finish, all of which are essential for repeatable and accurate gauging in production, toolrooms and quality control departments. The differential design allows quick functional inspection of the external thread and helps verify the correct engagement position and the suitability of the part within the prescribed tolerance limits. For consistent results, both the gauge and the thread should be carefully cleaned, protected from impact and contamination, and used by skilled operators, technicians and quality personnel in the metalworking industry. ACCREDIA certification or a calibration report can be supplied on request; this documentation may cause a delivery delay because the product must be sent to the inspection or certification body.