Test pens are handheld devices used to detect electrical voltage and continuity in circuits, providing quick and reliable testing. They are used in applications such as electrical maintenance, circuit troubleshooting, and safety inspections, ensuring accurate and safe voltage detection. Test pens offer features such as easy operation, high sensitivity, and durability, making them essential for verifying electrical connections and detecting faults. Their ability to provide reliable voltage detection makes them valuable for maintaining the safety and performance of electrical systems.