The Test Principle Of This Device Is The Same As That Of TM-421 Three-Round Tester. The Extended Version Will Upgrade The Electronic Display Screen And Setting Button To Touch Screen, Which Is More Convenient To Operate And Better Man-Machine Interaction. In Addition, Six Groups Of Inspection Systems Are Designed In The Mechanical Design, Which Can Carry Out Three Rounds Of Inspection On Six Cards At The Same Time. The Cards Are Designed For Quick Disassembly, Easy Installation And High Accurac