The RL-209 product is ideal for garages, warehouses offices or offices, doorman security reception desks for hotels and large machines, prisons, and so on. In these cases, it is required to install an intercom system for calls. Two-way phone Two-way intercom Two-way calls (both phones can calling button for the opposite party) and two-way intercom communication (the phone ringtone for the other party calls the phone, and the other party is talking) A two-line connection is available The voice of call is crystal clear and without network charges The effective distance can be as long as hundreds of meters. The dual-type intercom telephone can be used in offices and warehouses, communication rooms as well as family and other intercom lines. Very practical and reliable. AC power source (each phone has 4 batteries) and can be connected, (each only the phone is directly connected to 220V AC) Key Features:::: RL-209 Intercom system is an intercom door phone for double rooms. The system is energy-saving and no current. Clear communication via intercom door phone. Intercom set High-quality circuit for sharp and clear voices Talking distance is above 100m Easy DIY installation High-Quality With 30ft wire