Found an unrecognized black plastic cylinder (1-3/4 inch long X 3/8 inch diameter) labeled “S-10” in my Dad’s miscellaneous electrical ‘junk’ box. Self-tapping screws approx half inch long protrude slightly out each end. Resistance between the screw tips is 11740 ohms, and there is no concentric conductor insulated from the center. Any idea what this might be??