the invention relates to a system of a support element and at least two functional elements which can be used in the sanitary sector , with the support element being able to be coupled to each of the functional elements via a system interface and the system interface having a spigot - shaped element — at the support element side — with an outwardly biased latch element projecting out of said spigot - shaped element transversely to its longitudinal axis and the functional elements each having a tubular element corresponding to the spigot - shaped element and having a cut - out for the latch element .