As a result of a torn off part of the 9 V power supply, and forced disassembly, I was able to evaluate the quality of the control board - everything is soldered very neatly, it's nice to look at. If it were not for the jamb with the power connector, I would put 5. With its pros: An excellent device, considering that this is a complete analogue of the more expensive counterpart from Taiwan Hyperline HL-NCTU. All indication on the master, counterpart without indication - no need to run around to look. Feature - the case is assembled only on latches - not a single screw. Its cons: When trying to disconnect the newly installed test "Krona" - the attempt failed, the connector grabbed the battery dead. Subsequent attempts, even with a carcass, even with a scarecrow, to remove the battery ended in a cliff. The 9V connector had to be soldered from an old tester, which does not have such problems.