Ultrasonic Contact Impedance portable hardness testing is based on a 136 degree diamond at the end of a vibrating rod being depressed into the test surface at a fixed load. The difference in Ultrasonic vibration frequency is then calculated into a hardness value. The UCI test procedure is slower than the Dynamic Impact style, however the UCI method of portable hardness testing is portable, easy and accurate. It also has its own advantages when utilized for certain testing applications. UCI portable hardness testers are not restricted to large mass items like dynamic type portable hardness testers. These units can test metals as thin as 1mm and at a hardness value as low as 20HRC (75HB). They also excel at performing portable hardness tests on larger, harder metals as well. Another reason for the rise in popularity is due to the fact that the UCI method is categorized as Non-Destructive. That translates into less scrap parts/ lower mfg costs due to necessary inspections.