BodyGuardz announced the Portable Over-Door Camera during CES 2020.
The advantage of this product is that it supports most common household doors. Since it is in the form of a metal bracket that hangs over the door, there is no need for tools when installing. On one side, there is an optical camera that shoots everything outside the door, and on the other side, there is an LCD display that shows the scenery outside the door, and an additional camera. The camera starts when the doorbell rings and shows who is outside without opening the door. You can also have a microphone and speaker so both sides can talk.
This product is battery rechargeable and can be connected to home Wi-Fi, allowing two-way communication with the device by connecting to the front and rear cameras from the smartphone app. It is equipped with a cloud recording function, so you can save several hours and play it back in case of emergency. If you go on a trip, you can use it by hanging it over the hotel door. The price is $280. Related information can be found here .