The Extech TKG100 Thickness Gauges are designed in a compact, portable, durable chassis that is suited for use in the field. Ultrasonic technique enables non-destructive thickness measurements for mostly steel structures. It has several transducer options for high-temperature and difficult-to-measure materials. Comes with a 2 oz container of coolant, two AA batteries, a 5 MHz transducer, and a sturdy carrying bag.