Hot Button Instant Reusable Hot Compress, Neck

I love these. Not only are they great heat packs, they are great for science demonstrations (I use them in my science class too). It is not a chemical reaction, but a physical change. The solution inside actually "freezes" at 130 F but it is super stable, super saturated solution that requires some activation energy to start the crystallization. The purpose of wrapping in a towel when boiling is to prevent the plastic from touching the metal pot directly and melting. You have to melt all the crystals (even microscopic ones) to reset the fluid, or the crystallization will start again as soon as it cools to 130 F.

I use these many times a week. Ive purchased a few throughout years & these seem to be upgraded. I like the quality & also the fact that it goes back to liquid state faster

I bought it for back pain. The shape of it is good and it stays on shoulders. That's about it, do not recommend to buy! It gets hot quickly but does not stay hot for long enough! after 20 min it becomes warm where you can feel it only directly on the skin. After 30 min from the time heated, it no longer warm!!! Did not return to original form after boiling in water.

Heats up quickly but doesn’t seem to last as long as I hoped. It takes a long time and energy to boil the element back to liquid state. I think a regular old hot water bottle will suffice just as well.

Hi there! Last about 45 mins, gets very hot fast - like 2 mins! I am happy with this item.

Seems defective seldom last more than two months and they all split at this same place. Have bought multiple times and they all split at the same place.

Great for neck & shoulder!

works as described, only you get about 20-30 mins of heat once activated

El producto me gustó en un inicio, aunque para volverlo a su estado original, lo debes de someter a una alta temperatura, pero como al tercer uso ya tenía orificios por donde se tiraba el líquido que tiene en un interior.

Calor agradable, tarea complicada hervir para reutilizar. Me funcionó como 15 veces y después ya no volvió a su forma original; ya no sirvió más. No lo recomiendo