1Easy to install, the doorbell can be pasted on the wall with strong adhesive paper, or you can install it freely according to your needs. 2Ultralong transmission distance, strong and stable signal transmission in large houses, coverage of up to 200 m when there are no obstacles, and visitors' doorbells can be answered at any distance. 3Multiconnection mode, by learning its code, outdoor bells can be paired with multiple indoor bells without interfering with each other. 4Low energy consumption and long standby time. The outdoor bell is powered by 4 alkaline batteries (batteries not included). It is very convenient to replace the batteries and can last up to six months. The indoor bell is powered by a rechargeable lithiumion battery and uses smart powersaving technology. 5Twoway voice intercom function, wireless voice doorbell, talk with visitors through twoway voice intercom, know who is visiting your home and talk to them. Item Type: Smart Call Doorbell Weight: Approx. 140g / 4.9oz Material: ABS Open Connection Distance: 200m Obstacle Connection Distance: 20-50m Two-Way Intercom: Support Wireless Distance: Approx.200m / 656.2ft Working Temperature: -20-55 Degrees Celsius Working Frequency: 467.6375MHZ (No Waterproof Function) Power Supply Voltage: 1.5V External Unit Power Supply: 4xAAA Batteries (Batteries Not Included) Internal Unit Power Supply: USB Cable Power Supply Volume Adjustment: Support Change Ringtones: Support Scope of Application: It is suitable for residences, factories, hotels, hospitals, tea houses, shops and public places. Operation steps: Press the intercom button, the button light is on, it means the machine is normal, the button light is off, it means the battery is not installed, you must install the battery first. When pressing the outside machine: a. The indoor unit will keep ringing without pressing the intercom button. b. Only after pressing the intercom button on the indoor unit can the intercom call Code pairing method: First press and hold the indoor unit and turn on the power switch for 5 seconds, then let go, the button light flashes quickly to enter the code matching mode, and then press the button of the outdoor unit indoor unit from fast flashing to off to indicate successful code pairing. The code matching method for multiple indoor units is the same. 1 x Indoor Unit 1 x Outdoor Unit(Batteries Not Included) 2 x Double-Sided Tape 1 x Screwdriver 1 x Manual