Features 1、Remote Operation: This intercom can be used at a long distance of about 1500 meters, without network, without wiring, turn on and use. 2、Various Functions: The intercom has internal waterproof design, equipped with large capacity battery, with 2 charging methods. 3、Indicator Light: This doorbell has a good feel of the keys, with intercom light and power light display, the user can see at a glance. 4、Large 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. 5、Multiple Modes: With two indoor units, you can switch between ringing call mode and intercom mode, when the intercom is used. Specification Item Type: Wireless Intercom Doorbell Material: ABS Battery: Inner Rechargeable Lithium Battery: 3.7V 1800mAh (with built in battery) External Rechargeable Lithium Battery: 3.7V 1800mAh (with built in battery) Use: Widely used in home, office, laboratory environment, etc., medical Working Temperature: -20℃-55℃ Transmission Distance: 1000m in the open, 20-50m across the wall Operating Frequency: 410M-490M Package List 2 x Inner Doorbell 1 x Outer Doorbell 2 x Charger 2 x USB Cable 1 x Power Cable 1 x Screwdriver 1 x Instruction