The MIP3 system gives you the ability to link up to 16 devices together. Compatible with previous MIP System generations. The 3rd generation in MIP System technology allows you to choose different sounds for different bell pushes and other transmitters with the flick of a switch so you can identify which door or room has been activated. Compatible with previous MIP System generations including 1st generation. Mini switches allow different sounds to be activated with 2nd and 3rd generation chime units. Waterproof bell push with battery included.