Check the listing for details. Greenlee GT-10 Circuit Tester. Condition: Used. Listed at 19.95 USD. The Greenlee GT-10 Circuit Tester is a compact and easy-to-use tool designed for electrical testing. Made of durable plastic and measuring just 3 inches in length, this circuit tester by Greenlee is perfect for diagnosing issues in various electrical systems. With its electric measuring technology, the Greenlee GT-10 is a reliable and efficient tool for professionals and DIY enthusiasts alike.