Those are the Reptile Basics Hide Boxes: http://www.reptilebasics.com/hide-boxes
The ones in Rob's picture are the medium size. I start with the small size for hatchlings to ~300 grams, then move up to medium until they're ~1000 grams and then graduate to the large size. My biggest female (~2200 grams) still wedges herself into the large size, but I'm sure would appreciate an upgrade to an XL if I gave her the chance.
Because we all love pictures, here are how my T8s are currently set up:
http://i152.photobucket.com/albums/s...-SnakeRoom.jpg