The wife got one about 6 years ago. She would be in it almost, it seemed anyway, every opportunity she could. It was a 220 max device that ran off a 110 outlet. (It only tripped it once)
Now, it sits in the room, collecting dog hair underneath. It has a car stereo with am/fm, and CD. It uses infrared panels, and is teak wood or something. Nice door, hardware, and windows in the door. It came in several boxes with the walls and ceiling pre-wired for lights, heat, etc. It even has a back rest to chill as you roast.
She hasn’t been in it since that first year, but will not get rid of it. I looked in, and the spiders told me to close the door because of the draft. She was in a female marathon/triathlete group and it came highly recommended. Apparently it worked for the first winter fine.
Like anything, it’s only as useful if you use it. Maybe it could be cleaned and the spiders evicted, but she hates spiders but knows how much that cost so it sits there. She banned me from it too because I sweat A LOT. 
The assembly went well, it worked flawlessly when she used it. Even the radio worked. I thought of putting more speakers in it to see if it would work better for her. Maybe a tv?
I’ll post the brand when I get back and can get it. Wish I could sell this one, but anyway…