Structure tester is material structure sorting machine for bearing balls based on eddy-currents principle. Terminal inside of control chamber or outside on HDT 3050 is used to control movements and set up the machine. The HDT can be part of AVIKO machine or operated separately. The current version of structure tester 02-19 is able to sort balls in two channels based on the structure of a material, considering different hardness, chemical components or heat treatment. Structure testers 30-100 can sort balls into 6 channels. When structure tester is connected to AVIKO machine, three of those channels are reserved for OK balls, one for ECT/EVT balls(crack defects), one for EOT balls (bad polish) and one for NOK balls with different material structure.