Both the CF card and the SD card fit - as shown in the figure - super in the compartments. Once inserted, they do not slip back and forth or even drop out. Everything holds bombproof and by the "rubber insert" the cards are super secured even with a fall of the box. Also the closure of the box keeps excellent .... because you have a woman already spend to open the box a little force. Whether it is really waterproof, I can not say. We probably will not even try, because it was not a requirement for us. At least now finally listen to the fumble to the individually packaged memory cards.