Billie,
Many of the newer heating pads will turn off automatically after 30 minutes or so.
We got one for my daughter from the PT place, TheraTherm. It's nice moist heating pad, but I still use my infrared one for my TOS /achy upperback stuff.
I see they are cheaper online than what we paid, but it was a billing/ins/clinic situation.
http://www.isokineticsinc.com/catego...roduct/cg_1032

Thermotex™ produces infrared heating to provide deep penetrating warmth for temporary relief of acute and chronic pain.
http://www.thermotex.com/index.htm