Review Content Planning ahead With two batteries, one can be charging while the other is in use. Just right for the traveler I purchased this for a family member who needs some comfort help on long trips. Terrific idea! it is a very good product. it is helping me to have less lover back pain. A battery with staying powe. With back warmer Im able to keep soothing heat on my back for long stretches. I would like a longer time between shut offs.