The two sides hold together by using the drying stand :) You flip it around and slide it down the grooves on the side to lock the fliphole closed.
I've had my white one for well over a year now and would love to try the black version. The onacups are also very highly recommended. I wrote a review here: http://factsandfriction.blogspot.com/2008/08/tenga-soft-air-cushion-onacup.html which is now the #1 result on Google for 'tenga onacup review' - go me :)
Jake - oooh you're that Jake! I've been stalking your blog for a while now.
We did have the Fliphole in its stand but maybe in all the new toy excitement we did it wrong, we'll see! Oh, and yay for Onacups!