Feature: 1. Long Distance Intercoming: Barrier free long distance call distance supports about 1000 meters, no network or wiring required, easy to use. 2. High Performance: Intelligent intercom chip, strong penetration, even if the doorbell is on the 1st floor, the transponder can be used normally on the 8th floor. 3. Humanized Design: Humanized design, equipped with intercom light and power lamp display, surface pattern convenient for fast communication operation. 4. Long Standby: Built in 2000 mAh battery, long battery life, press 5 times a day, call for 2 minutes, can work for about 6 months, indoor unit work for about 1 week. 5. Wide Applications: IP54 waterproof outdoor bell grade, small size, will not occupy too much wall space, can be used in homes, hotels, villas, factories, hospitals. Specification: Item Type: Wireless Intercom DoorbellMaterial: ABSOutdoor Doorbell: Battery Type: Rechargeable lithium battery 2000mAhx2 (built in) Working Temperature: -20~55°C Wireless Distance: 1000m/3280ft (barrier free) / 20-50m/65-164ft (blocked)Wireless Frequency: 410~490MHzWorking Hours: More than 8 months Waterproof: IP54 Product Size: Approx. 121.5x61.5x313.mm/4.78x2.42x12.32inInterior Doorbell: Battery Type: Rechargeable lithium battery 2000mAhx2 (built in) Working Temperature: -20~55°C Wireless Distance: 1000m (barrier free) / 20-50m (blocked) Wireless Frequency: 410~490MHz Working Hours: about one week Waterproof Grade: N/A Product Size: Approx. 115x55x20mm/4.53x2.17x0.79in. Package List: 1 x Outdoor Unit1 x Indoor Unit1 x Charging Base1 x Usb Cable1 x Screwdriver1 x Sticker1 x Instruction Manual