I bought this for my husband for xmas and he loved it, but it only lasted 6 weeks. The cable that connects to the (user provided) battery pack is very flimsy and he had to constantly shift the battery pack for it to work (because it has to be in the pocket) and now it doesn't recognize the battery pack at all.My husband runs cold, but works a desk job in an overly air-conditioned office, so maybe it's only meant for laborers outside who stand all day?He still wears the vest over his shirt because it fits nicely and is attractive enough to seem professional, but we would have bought an alternative if we were only looking for a vest.It sucks that it failed right outside of the return window though.