For those involved in assembly or repair work, quality control or any other kind of detailed inspection tasks, some form of magnifier is likely to be essential. The simplest of these is the Sherlock Holmes-style reading glass, which is available in various powers of magnification, and despite its simplicity, is a very useful tool. Other simple magnifying glasses include the jewellers' loupe and various pocket magnifiers, sometimes including illumination. Magnifiers that clip onto spectacle frames are available in monocular or binocular types. Magnifying glass lamps are rather more static, usually being affixed to tables or workbenches. The lenses can be positioned in the desired position, allowing both hands to be free. For increased levels of magnification, a microscope may be required. These have progressed significantly from the old school classroom versions and even the traditional types may be fitted with eyepiece video cameras. Modern digital microscopes take things even further, offering features such as full video output to a PC, or in some cases, video may be saved to a micro SD card. Many accessories are also available, such as lenses, LED lamps and fluorescent lamps.