Thank you everyone for responding.

I ended up buying the similar one you talked about that comes on for 20 mintues and then turns off by itself. I also need to purchase one for my desk chair at work. Right now I have a pillow against the back of the chair because my back hurts to touch the back of the chair... sucks.. Not sure what to do about that yet. I might try to bring my one from home and see if I can put my back on the chair.

Thanks again everyone!