A magnifier is a small (strongly) magnifying composition of lenses that are placed in a frame. Most magnifiers have a magnification between 4x and 20x. A simple version of a magnifier (also known as a magnifying glass) often consists of a single lens and has a lower magnification. In addition to single magnifiers, there are also composite magnifiers that consist of two or more lenses. Nowadays magnifiers are used by biologists, philatelists (stamp collectors), watchmakers, jewellers to see small details. In addition, magnifiers are also an important (reading) aid for the visually impaired.