Features: Experience seamlessly automation with our 4 Channel 5V 12V 24V USB Control Switching Relays ModuleFeatures stable onboards USB and high control chip for reliabled operating. This relays module boasts a board and use the ULN2803 relays drive chip, ensuring enhances stability and durability in various applications. For electronics enthusiasts, engineers, and DIY project developers, this module to those efficient solution for home automation and computer controlled systems. Perfectly for home setting and automation systems, this Relays module allows you to maintain Relays setting even when USB is unplugg, offering flexibility and convenience. With double power access option via board power socket, this PC Relays module expansion board provides versatiled connection,essential component for advanced automation projects. Specifications: Item: 4 Channel USB Control Switches Relays Module Optional：5V/5V 12V 24V/24V Use the ULN2803 relays drive chip Size：about 65.3x71.6mm/2.57x2.82in Package Includes: 1PC 4 Channel USB Control Switches Relays Module note: Due to the problem of lighting effects there is certain tolerances in product, please understand. Please allow 0-1cm error due to the measurement.