I first came across these snowboarding in Munich, I’d had fall grabbed them for my back. Couldn’t believe how well they heated individual charcoal type pads all sectioned off. Depending on what part of the body you need it for they stay warm for hours. The attachments on the lower back one acts like a firm comfortable bandage.
I bought these on iherb for my mums lower back pain, she loved it. I’ve used them for my period cramp I find it better than any heat pad, wear it front side. Bought other sizes for the family issues. Much better than a balm that leaves sent & highly effective relief, comport for injuries or muscles in need of tlc. Highly recommended but back only have 2 in pack.