This "on demand" wrist strap tester also functions as a common point ground for up to two wrist straps and a mat. When the wearer of a wrist strap touches the metallic pad, a path for current flow is completed from the wearer's skin, through the wrist strap, to the metallic surface, then to ground. This action will cause the green "TEST GOOD" LED to light (and the optional audible signal to sound) as long as the resistance of the circuit path is between 750KΩ and 10MΩ. The wrist strap being tested may also be plugged directly to the tester, or any convenient common-point ground. Although this tester may be mounted any place on the bench, a 10mm snap stud on the back of the unit allows it to be snapped directly onto a mat. This item operates on 120VAC and comes with NIST-traceable Certificate of Calibration.