It's one of those small, portable greenhouses you can get at Lowe's. It's basically a metal rack on wheels with a clear plastic cover that zips open at the front for easy access. It's small enough to keep in the house (though I had to put a light roof on the top because our orange tabby kept jumping on the top and caving it in). We added some inexpensive fluorescent fixtures for warmth and lighting. Our seedlings have done very well in there and we might get another for the outside when Spring gets here.
The picture below isn't mine, but this is what it looks like:
Temps hit 60 degrees in western PA three days ago, but on Friday they dropped to 15 degrees in the daytime. It's bitter cold outside with one to two inches of snow expected both Sat and Sun.
My kohl plants did not survive the extremes of icy cold and freezing moisture of January weather.
I like it. Just right to use in front of a patio door.