Tests for continuity of circuit with power off. Bulb in handle glows when circuit is complete. Quickly reveals shorts or broken circuits. Has pointed 3-3/4" pointed probe and 4" plastic handle with removable nylon cap that holds replaceable bulb (model No. 69131) and "AAA" battery (not included). 36" test lead with fully insulated alligator clip. Overall length from probe to clip is 43-3/4". Carded.