A tough plastic box houses one stereo jack input feeding 4 stereo jack outputs. The sockets are pcb-mounted, and there is an internal link to mono the unit. Used for example, for splitting headphone signals in music rooms, computer music recording systems and hi-fi systems, it will also work in reverse as a 4 into 1 passive combiner. Dimensions are 120x75x39 mm., weight 12 grammes. It also has two additional volume controls, operating on channels 1 and 4.