Jes,funny you should post this, cause i bought one at target last night for 4 dollars and something. It's just a plastic thing with a tray on top for putting in food. Sadly, 4 oz isn't much chicken or potatoe. I had a cooked sweet potato i weighed on it and it was about 1/2 of it was 4 oz I'm sure this would vary depending on the size of potato.
I think it was about 1/2 of my chicken breast was 4 oz too. that was cooked.