This small USB adapter lets you connect PTZ cameras using the RS485 interface to your computer. By using this little device you can control your Pan Tilt Zoom Cameras through the PC DVR card that you have. We have tested this with our Digicam cards which it works with very well. This is a pro level item, so if you are using it with a DVR Card other than the Digicam that we sell, please consult your DVR card manufacturer for help using this adapter.