Features: Square USB interface for stable connection. Using imported high performance USB control chip. Using special relay drive chip ULN2803, the relay works is more stable. Both board power socket and terminal can access to the power supply are convenient and flexible. When the power is connected, the relay can remain set even if the computer is turned off or the USB is unplugged from the computer. Support for WIN7, for XP 32-bit/64-bit system. PCB board production. Specification: Type: Computer Control Switch Relay Module Input voltage: DC 5V Input current: > 300mA Wiring method: NC/COM/NO Relay size: about 10 * 8 * 2cm / 3.9 * 3.1 * 0.7in Package List: 1 * Relay Note: 1. This product can maximum control AC 250V, 10A AC load and maximum DC30V 10A DC load