They have several selections, ranging from funny and obvious to ones that look like real books. I chose the "Decoding Binary" cover as a personal joke since I'm so terrible with computers:
They come in two sizes - small for Mass Market Paperbacks, and medium for Trade Paperback size. I received the medium size for review. You can use them for mass market paperbacks but it does look a little weird. Here's me putting the trade paperback into the cover - super easy!
The first trade paperback I put in worked pretty well but was just a bit too long to be totally covered... Honestly, this was my only complaint. I wish the large covers were about 1/2 inch longer. You can see how the edges stuck out past the paper cover a bit. I was able to bend the plastic cover so the entire book was still inside the cover, but the paper cover that hides the book didn't quite reach, and this was not a thick book:
You can kind of see the line on the left in this picture where I had to re-bend the plastic to fit the book:
I think they allowed for this to happen though, as there are two spots on the inside where you're supposed to slide the cover and thus it was able to fit.
Here's where I tried it with a MM Paperback. It's not as good - I'd like to try the smaller size cover for my smaller paperbacks. Here's pics of my MM paperback inside the medium cover:
Here is a sample of what they offer:
Pretty cute, right? I actually had someone approach me at lunch and ask if I was studying binary code! I love the idea behind these covers and will definitely use mine. I'll also order a smaller size for my regular-sized paperbacks too.
Here is their website, their prices are reasonable ($4.95/small and $5.95/medium) and they have several choices.