The installation of equipment or devices on machines to eliminate hazards to individuals created by operation of the machines. These usually consist of gates, covers, shields, housings, or deflectors. Machine guarding hazards are addressed in specific Occupational Safety and Health Administration (OSHA) standards for the general industry, marine terminals, longshoring, and the construction and agriculture industries. Machine guards are normally grouped into four categories: fixed barrier machine guards, interlocking machine guards (electrical, mechanical, or hydraulic), adjustable machine guards, and self-adjustable machine guards. Fixed barrier machine guards are machine guards that are permanent parts of the machine. They generally provide the maximum amount of protection and require the least amount of maintenance. Interlocking machine guards shut down the machine in use when the guard is opened or removed. These machine guards can also provide a maximum amount of protection, but can require more maintenance than fixed barrier machine guards. Adjustable machine guards are positioned or arranged to work with the size of the material the operator is working with. Adjustable machine guards are easy to disengage by the operator and generally require more maintenance than other guards. Self-adjustable machine guards allow the material being used in the machine to enter the hazard area and places a barrier between the operator and the material as it is processed. Once the material has finished going through the machine, the guard snaps completely back into place. Like adjustable machine guards, self-adjustable machine guards may require frequent maintenance, and often do not provide maximum protection. All machine guards must prevent fingers, arms, and any part of an individual from coming into contact with a hazard zone; they must be designed and installed correctly; and the machine guards must fit the machine it is used on perfectly. See also Adjustable Guard; Barrier Guard; Fixed Guard; Guard, Interlocking Barrier; Interlocking Guard; Point of Operation Guarding.