Item Type: Wireless Intercom Doorbell_x000D_Material: ABS_x000D_Battery: _x000D_Inner Rechargeable Lithium Battery: 3.7V 1800mAh (with built in battery)_x000D_External Rechargeable Lithium Battery: 3.7V 1800mAh (with built in battery)_x000D_Use: Widely used in home, office, laboratory environment, etc., medical_x000D_Working Temperature: -20-55_x000D_Transmission Distance: 1000m in the open, 20-50m across the wall_x000D_Operating Frequency: 410M-490M 1Remote Operation: This intercom can be used at a long distance of about 1500 meters, without network, without wiring, turn on and use. 2Various Functions: The intercom has internal waterproof design, equipped with large capacity battery, with 2 charging methods. 3Indicator Light: This doorbell has a good feel of the keys, with intercom light and power light display, the user can see at a glance. 4Large Battery Capacity: The doorbell adopts intelligent power saving chip, which can be used for more than half a year under normal circumstances after a full charge. 5Multiple Modes: With two indoor units, you can switch between ringing call mode and intercom mode, when the intercom is used.2 x Inner Doorbell1 x Outer Doorbell2 x Charger2 x USB Cable1 x Power Cable1 x Screwdriver1 x Instruction