It is a microwave bacon cooker (pretty sure that is not it's technical name but that is one of it's main uses). I got it at Wal-mart. It was a couple of dollars. If they have a bigger one than this, I would get it because this doesn't cook a lot.
Now wash and slice your potatoes thinnly (as thin as you can get). Toss in a bit of olive oil. Spread on the cooking sheet; do not overlap. Sprinkle with salt (or other seasonings if you would like) then microwave for about 3 1/2 minutes. It will depend a bit on your microwave. I put my last batch in for 4 minutes and it was almost too long. No need to flip part way through. After your time is up, allow the chips to just sit there for a minute or so longer. That is it. Crispy chips, not greasy, seasoned just how you like. Only trouble is you can't get enough of these.