With this hardware I can select Nav/Com frequencies and transponder codes very quickly when flying online without having to open the radio stack of the Aircraft I'am flying at the time,and using programes like VATspy & Servinfo I can pre-select ATC frequencies in advance prior to contacting them…..very helpful contacting departure ATC just after take-off when the workload is the highest….just hit the transfer button….from the tower frequency to departure in a split second…..for FS2004 you need to go to programes and select the FS2004 plugin once flightsim opens..as I think its setup for FSX best hardware addon I have ever purchased.