Anpress 2 pcs Battery Powered Audio Doorphone Intercom TL-109AC/DC Doorbell Set Villa Non-Visual Intercom Two-Way Radio Telephone Security System doorbell Operation distance 200m, 2-line connected, run wiring from point A to point B. Each handset connects to the other,with a new ABS plastic, durable Each phone has a call button. The caller pushes a button that will make the receving handset ring loudly, realize the two-way radio,the sound quality is clear, no noise They are battery powered,even worked in a blackout, and so far, months later with daily use, they are still going strong This is a decent and inexpensive intercom system that uses 8 AA (4 in each handset) and a double wire line screwed onto the back of the bases to connect each set together,clear communication via,easy to install Suitable for dwelling houses, tier buildings, multiple apartments, offices, factories and so on