The Phidget Interface Kit 0/0/4 is a simple usb device that allows you to control 4 relays via PC Software.
The Phidgets PhidgetInterfaceKit 0/0/4 Interface is a simple and quick way to add real world controls to any PC application. It is a fully assembled hardware controller that will give any PC, with a USB port and the Phidgets API, the ability to independently control 4 analog relay channels. Each relay channel is fully isolated, and can drive up to a 10 Amp AC loads (250VAC Max Voltage), or up to a 5 Amp DC loads (100VDC Max Voltage) reliably.
The Phidgets Advantage:
All Phidgets devices are supported by the Phidgets API. The Phidgets API is a universal Windows interface that allows any Windows Programmer to easily embedded Phidgets hardware control into their software. Through the API, any Windows programmer can control, and query (if applicable), the Phidgets Hardware via the USB bus. Phidgets also makes available a wide array of example applications that are intended to demonstrate how the Phidgets API can be utilized. Both the examples and the Phidgets API are available for download from the documentation page.