Package includes: 1 set of door phone system The product will be upgraded constantly, the appearance and colour may be changed, please don't mind. And take a consideration before place the order if you have request compatible with colour or appearance. It is suitable compatible with use in a household. When a visitor rings the doorbell outside, the indoor telephone rings, and the indoor telephone sets up to talk with the visitor. Tap the unlock button, and the electric control lock opens automatically, so you don't need to run to the door to open the door. Features: call/intercom/unlock (function) ● Two-wire intercom connection. ● With unlocking function. (Add two wires compatible with unlocking) ● The aluminum alloy outdoor unit has anti-oxidation and wear-resistant surface treatment, which is durable. ● The outdoor unit can fill in the name or number of the household, and is illuminated by LED lights. ● With excellent side tone elimination circuit, the intercom voice is clear. ●The effective intercom distance of wire diameter is more than 100 meters (2X0.3mm connecting wire). Effective intercom distance length of connecting line: 100 meters (2X0.3mm) 150 meters (2X0.8mm) 250 meters (2X1.0mm) 300 meters (2X1.2mm) Dimensions of outdoor unit: (H)157×(W)108×(D)46mm Embedded size of outdoor unit: (H)149×(W)100×(D)28mm