They do come with the Dunlop Biomimetic range. I have the single racket covers for both of my 300's. And I believe Prince still provide a full length cover for their rackets too, at least they do in the UK. But an alternative would be a 3 racket bag....theyre pretty slim.
"Tennis is just chess with balls."
Sometimes: Dunlop Biomimetic 300 - Sometimes: Prince Exo3 Graphite 93