The key to listening centers is the jackbox, the distribution point to the headphones. Califone gives more attention to this stereo jackbox with silver-plated contact points for a solid connection and moisture resistance, individual volume controls, rugged ABS plastic housing for durability, 1/4”and 3.5mm plugs.
“For connecting multiple headphones to computers, stereos, CD players. All you have to do is to plug the earphone into the jackbox and then plug the jackbox into your audio source. Volume controls are included on the jackbox. This device comes in handy for several students playing a video game or for a group of students working on a project on one computer.” The Gadget Girls Media Review powertolearn.com, 9/25/03