Feature:1. Wide Application: Wireless intercom doorbells is widely used in homes, hotels, villas, factories, hospitals, etc.2. Practical: It includes one outdoor doorbell and two indoor doorbells. When you press the doorbell outside, the two internal doorbells ring. You can reply by voice when you press TALK.3. Strong Penetrating Power: Home doorbells adopts intelligent intercom chip, which has strong penetrating power. It can be used from the 1st floor to the 8th floor, and the barrier free distance is about 1000m.4. Intelligent Design: Voice intercom doorbells adopt intelligent and humanized design, with intercom light and power light display, and the operation is clear at a glance.5. Working Time: The outdoor unit and the indoor unit both use 1800mAh batteries, and the outdoor doorbells work normally. It can work for about 8 months by pressing 5 times a day and talking for 2 minutes at a time, and the indoor doorbells work for about 35 days.Specification:Item Type: Wireless Intercom DoorbellsMaterial: ABSUses:Used in Homes, Hotels, Villas, Factories and Hospitals.Specifications: 1 Outdoor Doorbell and 2 Indoor DoorbellsOutdoor Doorbell:Type of Battery:3 x Rechargeable Lithium Battery 1800mah(built in)Working Temperature: -20-50Wireless Distance: 1000m (Barrier Free) /20-50m (Barrier)Wireless Frequency: 410-490mhzWorking Hours: More Than 8 MonthsWaterproof Grade: IP54Product Size:Approx. 121.5 x 61.5 x 313mm / 4.8 x 2.4 x 1.2inIndoor Doorbell:Working Hours: About 3-5 days.Waterproof Grade: N/ASize:Approx. 125 x 70 x 56mm / 4.9 x 2.8 x 2.2in.Package List:1 x Outdoor Machine2 x Indoor Machine2 x Charging Base3 x USB Cable1 x Screwdriver1 x User ManualNote:1.Indoor and outdoor units are shipped with built in batteries.2.Do not place the product in an environment with excessive corrosion, humidity and high temperature.