Item Type: Wireless DoorbellMaterial: ABSWireless Distance: Approx. 1000m/1094yd (Barrier Free), Approx. 20-50m / 65.6-164ft(Through the Wall)Operating Frequency: 410M-490MBattery Type: Built in 2 x 2000mAh Lithium Ion Battery (Indoor Doorbell with Outdoor Doorbell)Working Time: Outdoor Doorbell About 8 Months, Indoor Doorbell About 1 WeekSound Adjustment: 3 Gears AdjustmentPackage List1 x Outdoor Doorbell1 x Indoor Doorbell1 x Sticker1 x Charging Base1 x Type C Power Cord1 x Round Hole DC Power Cord 1 x Screwdriver1 x Instruction ManualManual measurement, please allow some errors.1Wide Wireless Distance: Wireless doorbell can up to 1000 meters of barrier free distance or 20 to 50 meters of through the wall distance to meet the needs of many scenarios. 2Waterproof Design: Wireless intercom doorbell adopts waterproof design, which can be used safely and durably in different seasons and weather. 3Long Battery Life: The smart wireless doorbell can work for up to 8 months (outdoor) or 1 week (indoor) using the built in 2000mAh lithium ion battery. 4Two Way Talk: This doorbell supports two way talk for easy visitor access, thus you know who is visiting your house and talk to them conveniently. 5Clear Sound: Includes 1 outdoor doorbell and 1 indoor doorbell, providing wireless large range calls with stable transmission signal for clear sound.