A mobile phone video amplifier (commonly known as a 3D phone screen magnifier) is a portable, unpowered device designed to enlarge your smartphone's display. Using a specialized optical sheet called a Fresnel lens, it expands your phone's screen by 2 to 4 times its original size, simulating a tablet or mini-theater experience. It provides a larger image while filtering blue light to reduce eye strain, but relies entirely on your phone's internal speakers for audio unless you purchase a hybrid model with integrated Bluetooth speakers.