Radar station N-21 is being used in the Polish Army since the late eighties of the last century. It is the predecessor of the station N-22. Both stations are designed for use by antiaircraft subdivisions, a part of antiaircraft, mechanized and armored divisions. The device was placed on a special tracked vehicle SPG-1M, so, just as tanks and infantry combat vehicles, is able to move in very difficult conditions. Powerful, for an radar station, armor allows the unit to work during combat conditions.