Description: Adopt USB HID mode for relay control,suitable for various occasions and professionals. Strong anti-interference ability, diode freewheel protection. 5V,12V,24V optional. With power-on memory; power indicator light; a normally open and a normally closed contact. Relay contact adopts double-sided thick wiring, which can pass large current and is safe and reliable. Widely used for all MCU control, industrial sector, PLC control, smart home control,etc. Specification: Product Name: 4-Channel Relay Module Output Channel: 4 Working Voltage: 5V/12V/24V Relay Contact Capacity: AC 250V 10A, DC 30V 10A Total Size: 78x50x19mm/3.07x1.97x0.75inch Material: Electrionic Components Package Includes: 1 Piece 4-Channel USB Relay Module Note: Color maybe slightly different due to different monitor. The above size is measured by hand, please allow slightly difference. Thanks !