Replacement PCM vests, single PCM packs and complete sets of packs.
You can also create your personal customized set of PCM packs: Cooler packs on your back and thinner ones on your chest? Or the other way around? Just order 4 individual packs in your preferred temperature and cell configuration.
It's also possible to order a PCM cooling vest with only two packs on the chest or on the back: Simply order a replacement vest and add two single PCM packs of your choice.