The big one is OK, Ping, but if you're going in that direction take a look at the "C" version (new, color screen). It fits a "26", but comes with an insert for a "18". The non-color version (non Nano) also had issues with the bottom screw being the ground, so some folks were getting little shocks from it.
I prefer the Nano size of that same mod, in any color but red (issues with the battery caps on the red ones). I have one, and like it a lot, but it's given some folks fits.
Here are a couple of shots so you can get a feel for the size of the Nano. All are wrapped (VaporSkinz clear or pattern on the red one).
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