External & Internal Bell: Our bell has an external bell and an internal bell. By learning the code to pair the external bell with the internal bell, you can pair one external bell with N internal bells without interfering with each other. Intercom Function: Our wireless voice doorbell, talk to visitors through two-way voice intercom, you can know who is visiting your home, talk to them, let them know that I am going, please wait, the speaker can be adjusted, the sound is clear, you can Use as a mobile phone. Stable Signal: This doorbell has a stable signal and super penetrability, wireless long-distance up to 200M-strong and stable signal transmission in a large house, covering a range of up to 200M (barrier-free , Accessible). Low Power Consumption: Low power consumption, standby time for outdoor range hood up to six months. The outer cover is powered by 4 alkaline batteries, the battery is easy to replace, and the inner cover is powered by a rechargeable battery, which is also very convenient for charging. Easy To Install: The doorbell is easy to install and can be fixed to the wall using adhesive tape. It will be installed quickly and will not take too long. Specification: Indoor unit input voltage: 5V 1A Wireless frequency: 467.6375MHz Transmission distance: outdoor bell:200m indoor bell:5-50m (without any obstacle) Size Chart: Size:approx.100x60x14.8mm/3.9x2.4x0.6inch Package Includes: 1 Piece Indoor Unit 1 Piece Outdoor Unit 1 Piece Screwdriver 2 Pieces Double-sided Adhesive 1 Piece USB Charging Cable 1 Piece User Manual(English) Note: Due to the difference between different monitors, the picture may not reflect the actual color of the item. Due to manual measurement, there may be 1-2cm error in size.