The buttons are one of the nicer features of the Apple leather case. On many of the leather cases (Kulor included), they simply cut away the areas around the buttons in order to give access to the phones buttons.
With the Apple leather case, the volume buttons are laser cut, color coordinated buttons that cover the phones original ones, the mute button being an exception. Maybe because its a switch rather than a push button?
The
Lopie cases, another for this list, seem to do the same as Apple.
Elago is another with the open ended bottom.
It is hard to tell from the photos, but if you watch the video, you can see the
Twelve South Relaxed Leather case is also open at the bottom.