The TKG100 is a base gauge offering a simple user interface packaged in the same custom molded high density plastic case with rubber keypad as the other more sophisticated models. This gauge offers reliable, accurate thickness readings on mostly steel structures with access to only one side.Extech offers Thickness Gauges designed in compact, handheld, rugged housing ideal for field use. The ultrasonic technology allows for non-destructive thickness measurements for primarily steel structures.