Sauter td 225 0 1us ultrasonic thickness meter sauter td 225 0 1us p the sauter td 225 0 1us is a thickness gauge that uses ultrasonic waves to exactly measure the thickness of a material the gauge has an external sensor for those hard to reach measurement points p p the td 225 generates high accuracy results within a measurement range of 1 2 to 225mm with sound velocity of 500 to 9000m sec the measurements are then displayed on the clear to read lcd screen in either inches or mm p p