www.campmor.com has two heat packs available. there is a set of 4 disposable packs @ 2.99( 2.50 for two or more) that last up to 7 hours. they have a reuseable pack, but it only lasts one hour and must be boiled to recharge. 4.99( two or more @ 3.99) I know www. MajorSurplusNSurvival has a good selection, but I couldn't locate the packs on the website. Id drop them a line for details. They had two sizes in combination packs.<br><br>