The Lisle Corporation Relay Pro 12-24V Relay Tester, No. 60150, tests relays by simply clipping the test leads onto the relay terminal pins using a 12V or 24V DC power source. It tests a wide range of four and five pin relays including shielded, non-shielded, relays with different pin sizes, and four pin normally closed relays that other testers may incorrectly show fail. The tester automatically determines the relay configuration so the fully insulated gator clips can be connected in any order. Eliminates guesswork because you don’t need to connect to specific pins, like other testers. 45" power leads with heavy duty gator clips provide a secure connection to the power source.