I have a very bad back (2 herniated discs and one bulging disc). My doctor and PT are against heat on a back bad. Instead, they insist on cold only.
I have those flat, rectangular cooler packs for lunches. I strap those to my back with an adjustable back-brace I inherited. Works well and is infinitely cheaper in the long run.
Also, the Thera Cold pad looks to be $19.99 on WalMart.com.
"Look son, there comes a time in every man's life when he has to make a decision. Do you want to be big, powerful, jacked, yoked-up, have women everywhere want you and men fear you . . . or do you want to do crossfit?"