This test pen has: 1. Self-checking function, check whether the electric pen is working normally, and can detect the connection and disconnection of the line; 2. It can detect alternating current and direct current at the same time, and distinguish the positive and negative polarities of direct current; 3. AC live wire and neutral wire detection can distinguish and distinguish the neutral live wire; 4. This paragraph has the characteristics of high sensitivity and can be used for induction detection operation; 5. The sealing function IP56 waterproof level is added to prevent the internal parts from getting wet and improve the service life; 6. Increase the brightne of the light-emitting diode (LED), which is convenient for users to clearly distinguish; 7. The resistance value of the resistance is improved, the safety range of the test is effectively improved, and the safety is increased; 8. The pen-hanging design is convenient for users to carry; 9. The blade is made of CRV alloy steel, which enhances the firmne and can also have the function of a screwdriver; 10. The circuit board is made of advanced engineering board, and the design is reasonable, which enhances the performance of the test pen. Product parameters: AC voltage (contact) test range 12-250V; DC voltage (contact) test range 12-400V; AC voltage induction test (non-contact) test range 70-1000V; voltage frequency 50-500HZ, acce check 0- 20M.