Suitable for use with power on. For 6 and 12V automotive systems only. Locates shorts, earth and open circuits. 1m lead. Super sharp tempered steel probe to test through wire insulation. Probe length: 45mm.Super sharp tempered steel probe circuit tester to test through wire insulation when power is switched on. Tests 6 & 12V automotive systems only, locates earth, short and open circuits. Tester is fitted with a 1m lead for convenience, 45mm probe and a strong transparent plastic handle.