Sounds very similar to the Pure Highway products. I have a Nextbase DAB+ adapter in my SL, it works great and only cost £32.I just had DAB fitted to my W204 today from a company called justconnectme the product I have is the justdrive it was £180 and is an FM transmitter so it uses a spare FM signal the chap has programmed it to preset 0 so when my daughter is in the car and she doesent want to listen to dads old music I can just hit preset 2 for kiss fm and then back to 0 for DAB the gadget is behind the dash somewhere you wouldn't know he has been in the car apart from a thin aerial stuck in the top left corner of the screen,the gadget works by remote so you have a tiny remote control which you can search and store your DAB stations on,i have had this thing fitted on 4 of my previous cars and haven't been able to fault it once.