This is a 9D mobile phone screen magnifier (Model F8). It works like a projector screen, enlarging the display up to 3-5 times for a better viewing experience.
It uses HD zoom optical technology, often with an acrylic lens.
It does not require any batteries.
It can help relieve eye strain when watching videos for a long time.
Viewing distance is recommended at 1-2 meters for best results.