I get my chicks delivered to my office so I have to transport them from my office to my home after they've warmed up and eaten all day in a portable brooder. Sometimes it's dang cold outside so I warm up my car as best I can, but I didn't have a separtae heat source until my husband handed me an option. "Therma Care heat Wraps" They are large heat packs meant to cover the lower back. I find one or two, depending on how many chicks I'm transporting, of them under a towel keeps them toasty warm without overheating. Much , much better than the little chemical hand warmers I've tried in the past.