This Mercury 2 Wire Door Phone System allows you to talk to visitors before opening the door. It features an additional function to allow the opening of an electronic lock, making it ideal for domestic and business applications, and particularly helpful for the elderly or less mobile. The system includes an intercom with sharp, clear audio and 16 different ringer options. The outdoor unit is weatherproof (IP44 rated) and has a backlit nameplate. Please note that the cable is not supplied. The system is supplied with an adaptor and wall mount brackets. It supports a maximum distance of 100m when using 2 x 0.75mm² cable. Power supply: 12Vac, 1000mA Outdoor unit dimensions: 160 x 113 x 68mm, weight: 350g Indoor unit dimensions: 210 x 85 x 60mm, weight: 340g