The S & G Tool Aid Circuit Tester with Digital Display, No. 28350, is designed to measure 6, 12, 24, and 48V systems. The tester quickly and easily checks voltage, power, ground, and circuitry without the need to hook up complex equipment. The display numbers are tall and easy to read. A red LED indicates power (+) and a green LED indicates ground (-). The lead wire stretches up to 11' for use, then automatically retracts. The tester is computer safe and draws less than 10 milliamps at 12V. A heavy duty ground clip with insulator and a sharp stainless steel probe are components of each tester.