Plastic coverings for game and console cardboard boxes

Many collectors in Europe and Japan cover their game and console boxes in plastic, but not sure what the plastic is they use. I believe this plastic protects the boxes from dust and other nasty stuff that can damage the boxes. Does anyone know what the plastic is they use and where I can get them?

 

Is the plastic rigid and shaped like the thing it's protecting? If it is, I've seen them on eBay.

 

I use these
http://www.sentinel64.com/

 

Well in the UK there's a ebay seller (and webstore) run by sentinel64 who makes the best quality cases i've seen yet (at a good price anyway) there made from PET and are very good. Since he started selling them i've gone back to collecting boxed n64 games again and they look very very good in these cases and should keep them protected for a long time.

 

I just posted their website

 

You guys misread what I'm talking about, however you're close.

Not CASES, covers. They are similar to the plastic covers that you get with Japanese music CDs, except they come in various sizes. Just not sure where to get the really big ones for console boxes.