Receivers are commonly housed in a half-rack configuration, so that two can be mounted together in a rack system (that is to say the receiver is enclosed in a box 1U high and half-width, so two receivers can be installed in 1U). For large complex multi channel radio microphone systems, as used in broadcast television studios and musical theatre productions, modular receiver systems with several (commonly six or eight) true diversity receivers slotting into a rack-mounted mainframe housing are available. Several mainframes may be used together in a rack to supply the number of receivers required.