Biddle 250260 Megger Direct Reading Earth and similar items

BIDDLE / AVO / MEGGER 250260 GROUND RESISTANCE / EARTH TESTER MISSING TOP KNOB This is a estate find and was told that it works just fine. I have no way of testing it, so I am selling as is, NO returns. CONDITION IS VERY CLEAN APPEARS TO HAVE BEEN USED VERY LITTLE. The Biddle Megger three terminal ground resistance tester is the economical choice for electrical contractors, plant electricians, telephone and CATV technicians making routine ground resistance tests on single electrodes and other simple grounding systems. The instrument is easy to use for quick measurement of resistances from 0.5 to 500 ohms Features: Three-terminal ground resistance tester Easy to operate Quick measurement of resistances from 0.5 to 500 Ohms Reads directly in Ohms on a single range scale Stable calibration Checks probe resistance and battery condition Battery powered Limits output to 50 V open circuit, 5mA short circuit Weighs less than 3 lb.