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. Specification: Item Type: Intercom Doorbell Mode: H8 Material: ABS Battery: 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 55℃ Transmission Distance: Open Areas: Approx. 1000m / 3280.8ft Partition Wall: Approx. 20 to 50m / 65.6 to 164ft Operating Frequency: 410M to 490M. Package List: 1 x Internal Unit 1 x External Unit 1 x Charger 1 x USB Cable1 x Power Cable 1 x Screwdriver 1 x Manual