Feature 1 Work Range: This intercom doorbell can realize intercom at a distance of about 1000 meters in open areas, and 50 meters in the partition. It can almost meet most of the intercom needs between any two rooms in your home. 2 Waterproof Performance: This intercom features a waterproof performance that rest assured to install it outdoors, in your bathroom, kitchen, etc. 3 Light Indicator: Comes with intercom light and power light display, you can monitor the statues at a glance. Convenient for you to make adjustments in time! 4 Energy Saving Chip: With built in energy saving chip, after the intercom doorbell is fully charged, it can be used for more than half a year under normal conditions. Not working at ordinary times, no power consumption. 5 Wide Application: This intercom doorbell is widely used in home, office, laboratory environment, etc. You can also take it for other places use.Item Type: Intercom DoorbellMode: H8Material: ABSBattery: Internal Unit: Rechargeable lithium battery 3.7V 1800mAh (with built in battery)External Unit: Rechargeable lithium battery 3.7V 1800mAh (with built in battery)Use: Widely used in household, office, laboratory environment, etc.Basic Parameters:Working Temperature: - 20 to 55Transmission Distance: Open Areas: Approx. 1000m / 3280.8ftPartition Wall: Approx. 20 to 50m / 65.6 to 164ft Operating Frequency: 410M to 490M Package List1 x Internal Unit 1 x External Unit 1 x Charger 1 x USB Cable1 x Power Cable 1 x Screwdriver 1 x Manual