The EES TG 11 is a multi purpose industrial type ultrasonic thickness gauge. It uses the transit time ultrasonic wave propagation principle to measure the thickness of materials of several types including metals and plastics. The probe acts as a sender and receiver of a 5 MHz ultrasonic signal and an internal counter calculates the time taken for the signals sending and receiving through the solid being measured. The EES TG 11 can be set at different acoustic velocities depending on the material being measured. The instruction book includes a table of acoustic velocities for some of the commonly used materials. In the absence of the acoustic velocity of the material being measured, it is still possible to measure materials of this kind if a representative sample is available of a known thickness.