The 19’’ LEO–alpha housing concept is applied with an intake of subracks, i.e. 19’’ insertions without lateral connectors. The attachment occurs via a freely swinging 19’’ rack screwed tightly to the housing or slid in via an oscillating frame (system integration outside the housing). The frontal and rearmost mounted frame* (Zarge) and especially also the lateral functional bays provide extreme form stability with simultaneous protection of spring-loaded handles, quick release clamps, displays, and other individually integrable functional elements. To avoid damage in transit all extension units are arranged within one contour.