Cable trunking types AT-1D and AT-2D are used for separate energy and communication installations. Type AT-1D has one additional level in a separate trunking, while type AT-2D has two. The energy installation is led trough the main cable trunking, while the communication is placed into the additional levels. Sockets for both installations are in the main level, except in type AT-1D 220, where sockets for communication are installed in its own full size trunking level. The standard colours are RAL 9010 and 9006. All other RAL colours are available on demand. The length of a single trunking base is 2 m.