The Channel Vision DP-Series Panasonic Compatible Intercom Door Speaker is a 1/4" solid brass door plate that interfaces with a telephone entry controller to provide communication with the front door. It is compatible with Panasonic"s popular KSU phone systems and comes with a surface mount box. This Intercom Door Speaker is compatible with the DP-RBOX-III flush mount box, which is sold separately. FEATURES: 1/4" thick solid brass plate. Discrete speaker and microphone. Fits the DP-Rbox-III flush mount box, and the DP-9001, DP-9002 surface mount boxes. TECHNICAL DETAILS: Dimensions: 6.5(L) x 4.375(W) x 0.25(D) inches. Impedance: 8 Ohms. Power Peak: 0.2W. Frequency Range: 500 Hz- 4.5 kHz. Waterproof: Yes. NOTE: DP intercoms do not fit standard junction boxes. COLOR: Copper.