The use of the telebrineller hardness testing system is quite simple. The principle is to use a test bar of known hardness that is plus or minus 15% of your expected hardness value. The test bar is inserted into the cost effective portable hardness tester and the unit is placed on your specimen. Below the test bar sits an impression ball. The operator will strike the anvil with a hammer to indent both the specimen and the test bar. Using the microscope, you can then measure the diameter of indentation left on your specimen and compare it on the included chart to find your BHN brinell hardness value.