The Model 275A Ground System Tester measures the resistance of personnel grounding systems including wrist straps and heel straps. It also measures work area grounding systems (table mats and floor mats), and indicates if the resistance is high (open), low (hazard), or within acceptable limits to control damage to sensitive components due to electrostatic discharges. Testing is as easy as pushing the test button and observing the color-coded indicator lights. The safe operating limit can be set at 10M or 100M ohms using a switch on the front of the instrument. The instrument is supplied with a ground cord, and an optional leather carrying case is available.