The most popular portable hardness tester in the world is the Leeb hardness tester, however, there are tasks that using this method is very difficult or even impossible to solve. This is due to the physics of the method, which assumes the massiveness of the testing object, to ensure the inertness of the product when the Leeb’s impact body hits the surface with a given force. In order to solve a wider range of tasks on the rapid measurement of metal hardness, our company offers hardness testers that implement the method of ultrasonic contact impedance (UCI) in accordance with ASTM A1038. A vibrating rod (mechanical resonator) with a diamond tip acts as an indenter in these devices, when it indent into the material, the base frequency of the resonator changes, on the basis of which the hardness is calculated. This method has proven itself around the world and has been used in industry for over 50 years.