The Model EJ-2 is a compact multi-input adapter that compact & light weight accepts signal level input from either a laptop computer, audio cassette player, CD player, DVD player, or video tape player for insertion into an existing P.A. system. It is designed to provide the user with an easy to use, easy to carry, high quality interface for the audio content of any type of presentation, while providing the necessary matching and isolation to protect the PA system. no batteries or external power required The EJ-2 is a passive device, no batteries or external power sources are required for operation. The EJ-2 includes cables with a 3.5mm stereo plug and a pair of RCA plugs for making connection to the laptop or audio content for other audio/video device, and a standard 3-pin XLR for presentations made easy connection to the microphone input of an existing PA system. It also comes with a nylon carrying case. An instruction card comes stored in a pocket of the carrying case. The EJ-2 does not have its’ own volume control. If you audio interface for need to adjust the volume of the audio, you can either laptop computers use the volume control on the actual audio/video device or adjust the volume using the control associated with the existing PA system.