The cradle (molded area where the Kindle sits) is very sturdy and you won't have to worry about the Kindle popping out. The cradle is made out of a sturdy plastic and has a rubber perimeter that holds the K4 in place. The cover will not bend where the cradle is so no worry about it popping out accidentally. It actually takes a bit of work using both hands to remove the K4 from the cradle.

If you look at the photos in my post above you can see that the rubber perimeter grips and holds the K4 in the cradle, and yes the K4 just snaps in.