Features: 1.Two Way Voice Doorbell: The perfect combination of dual indoor and outdoor intercom allows you to communicate with visitors outside the door. Allows you to identify visitors outside the door based on sound 2.Easy to Use: The doorbell adopts one button call. Hold down the talk button and speak, release to stop. Click call button, the other voice caller rings. 3.Loud Volume: The speaker is loud and adjustable, and the sound is clear. Outdoor open free line communication distance is 500 to 1000 meters. 4.Long Standby Time: The doorbell is built in 1800 mah polymer lithium battery, In general, they work for 30 seconds five times a day for about a week. 5.Automatic Charging Stand: The doorbell is placed on the charging stand when it is in standby mode. The intelligent automatic charging takes about five hours and the power is never off. Specification: Item Type: Wireless Intercom Doorbell_x000D_ Material: Abs_x000D_ Battery Type: Polymer Lithium Battery_x000D_ Battery Model: 103450_x000D_ Battery Capacity: 1800 Mah_x000D_ Power Supply: Polymer Lithium Battery (Delivered with Built-In Battery)_x000D_ Battery Powered: Dc5v/1a_x000D_ Operating Temperature: -20 Degrees Celsius~ 55 Degrees Celsius_x000D_ Transmission Distance: About 1000 Meters Open, 20-100 Meters Partition Wall, Floor 1 ~ 8 Floor_x000D_ Operating Frequency: B Gear Frequency 462mhz a Gear Frequency 434mhz_x000D_ Working Time: Charge for About 1 Week_x000D_ Charge Time: About 5 Hours Full_x000D_ Music Ringtone: 38 Ringtones_x000D_ Ring Volume: 3 Levels of Adjustment (To Adjust the Volume of the Machine)_x000D_ Call Sound: Level 3 Adjust Call Level (Adjust Volume Button When Talking) PackageList: 2 x WirelessIntercomDoorbell 2 x Charging Stand 2 x Charging Cable 1 x Instruction Manual