Flat channels are used when only a shallow construction height is available for the installation of the drainage system. Flat channels have an especially shallow construction height to suit this type of situation. These channels are connected to trash boxes in the same way as channels with the standard construction height; also, the gratings used are the same as those used for standard channels. It is also possible, in certain circumstances, to use flat channels in open construction, i.e. without gratings (see also dish channels).