Not sure what the brand was, but they were of the larger variety (large enough that one would cover your lumbar area) and reusable-I think they just put them into boiling water or something like that to recharge. I will see if I can dig up the info they passed along about them a few years back. The only problem either of them ever reported with using the heat packs was placement to prevent skin burns (seems like they were wrapping them in something to avoid direct contact.) They were doing some 3+ hour dives in 68-72F water wearing 3mil suits, and were warmer than some folks, doing less in dry suits, when they surfaced.