Description: It is a 4 Channel USB Switch Controller. Board power sockets and terminals, two power access methods are convenient and flexible.  After the power is connected, even if the computer is turned off or the USB is unplugged from the computer, the relay can also remain set. Feature: PC free drive control 4 channel control circuits Dual power input The relay works stably Specification: Product Name: 4 Channel Relay Module Input Voltage: DC 5V 12V 24V option Input Current:300mA(Max) Connection Method: NC/COM/NO Work Temperature:-25?~85? Work Humidity:5%~95%RH Size:72*72*20mm