If the unit is in need of support, calibration or repair, initiate the RMA system with us and we will be delighted to aid. The autozero button and electronic Show tremendously simplify calibration of extensometers. The 3590 calibrator is beneficial for extensometer calibration and verification with exam units. Shopper Gratification: https://www.nathanisoconsulting.com/iso-22000-certification-consultant.htm