Only the following restrictions must be noted at present: Older receivers of types FES 14 and FES 24 can only be addressed via buttons 1-4 on the handheld 8-channel transmitter FSH 8. The repeater FR3 U1 can only be combined without restriction with the current transmitters and receivers (i.e. from series FS 3 / FE 3 / FD 3 onwards).