Features: Premium Material: This main body is made of plastics material, the discharge pen is made of freeze-resistant silicone, which is fine insulating and highly elastic. Multi-functional design: The capacitor discharge pen is in the maintenance of products, you can switch the power supplys in the high voltage capacitor or AC capacitor of the stored electricity quickly discharge, so as not to be in the maintenance of the remaining electric shock for protecting the operator and the product from being damaged. Easy to Use: Use a constant current source circuit for rapid discharge, and use red and black meter pens that do not distinguish between positive and negative, the meter goes directly into the capacitor to be discharged above, and the discharge does not create sparks. LED Indicator: There is an LED indicator, LED on, which indicates that the capacitor still has power, and LED off, which indicates that the power has essentially been fully discharged. Buzzer Alarm Feature: Version V4.0 adds the buzzer alarm feature, where the buzzer sounds when there is electricity and does not sound when there is no electricity. Small Portable: This product is small, and easy to carry, as a professional repairman it is necessary to have a ready-to-use product to protects the product and their own safety. Applications: The V4.0 version of the meter pen is suitable for maintenance and repairing use, as is the inverter air conditioner discharge with PFC correction. Note: The size of the discharge capacitor depends on the voltage above the capacitor, the voltage is high, the capacity of the discharge pen can be put to reduce. In addition, after the LED is off, in order to discharge the electricity more clean, please continue to discharge for 10 seconds; disconnect the 220VAC power before discharging, otherwise it is easy to damage the discharge pen.