4.9 Illegal Equipment.

Any swimmer wearing any artificial propulsion device, including but not limited to fins, gloves, paddles, or floating devices of any kind shall be disqualified.

Info@USATriathlon.org

It doesn't appear to be listed, but I would write to clarify that.

Crazy, no, it won't damage her wetsuit. They are made for that, plastic heat packs that, I think, you boil, cool off, then click this metal disc thing inside it that makes it heat up when you want it to. Then you re-boil it to reset it? That's the kind I've seen, anyway.

Nanci