Jana, if you are asking about the Thermarest, it is a self-inflating sleeping
pad - sort of an air-mattress with foam inside. They are principally used for
backpacking, since they can be rolled up fairly small but still provide, at
least in my mind, a comfortable bed.
You can get them in a variety of styles and sizes, and there are a number of
different manufacturers offering them (I think even Coleman has one).
The original Thermarest is made by Cascade Designs:
http://www.cascadedesigns.com/