Shop images / files / the book
This file appears as a yellow ball as "kittens". At age 100 they show what they're supposed to look like.
There are 2 types (T1 T2) that each have 4 different adult versions. All have the same yellow kitten size even though they're different sizes as adults.
If you want to know which one you might be buying, there's a small book at the bottom of the page you can try to match the image up to. Yes, it's supposed to be hard.
There'll be new ones added if the shop gets empty and there's nothing to stock it with.
Trading
You don't have to do anything more than just buying one. Everything else is optional, just something to pass time.
If you're bored with the file, took a gamble and don't like what you got, or someone has the one you wanted, you can trade these around with each other.
You can use the "Trade Gems" forum to trade files bought from the gem shops.
There has to be some kind of trade and not just giving them as gifts / freebies. ie 1 for 1, 1 for 5, 1 for 30.
If you don't like what you got and you don't want to trade for another delete or send the file to the PUGS email.