HEAT WAVE Green 2-Pack Instant Reusable Heat Packs – Medical Grade, Large (8" x12”) - Made in USA

My husband has severe back pain and uses this as a portable and reusable option to provide comfort.The recharge isn't -hard- but it takes long enough that you can't just do it before running out the door in the morning; you have to think ahead. That said, it achieves a very nice heat output and duration, is durably made, and has recharged perfectly every time. While it's initially much more expensive than even a box of disposable instant heat pads, the ability to reuse it makes it worth it.Make sure you recharge it in a heavy duty pan where heat is well distributed and you're less likely to have intense heat spots that might melt the outer shell; also make sure the water is already hot before you put the pad in it.I haven't tried with this one, but I have been able to recharge a small handwarmer version (same brand) with hot water heated in a microwave while I didn't have access to a stove. It might not work as well with a larger pad, but if you want to try, the method is basically to have two microwave-safe containers large enough to cover the pad with water, heat one (WITHOUT THE PAD - NEVER PUT THE PAD IN THE MICROWAVE), then heat the other while the pad soaks in the first, and keep switching and reheating the 'off' container's water until all the crystals have melted and the gel is entirely opaque again. Note that if the pad begins to cool before -all- the crystals are 'melted', it will reharden and you'll have to start all over; I do not recommend this method.

EDIT: I had to throw it away today only after using it for three times. It left sand like particles all over my bed sheets. It also doesn’t stay hot for very long. The concept is cool though.I am using this right now. It is awesome. So easy to use. It’s a little on the hot side for me so I wrapped it up in a shirt. I am very happy I purchased it! Works great!

These products are great to help warm up my disabled son who has trouble regulating his body temperature. The little button that you click to activate can be a little difficult sometimes, but as soon as it activates it heats up very quickly and lasts a long time. When the heat process is finished, it does not become rock hard like other Insta packs I have tried. This is actually the second time we have purchased this product and as long as it is available, we will continue to purchase again if needed.

I bought these for camping. We camp in the Rockie Mountains from early spring throughout late fall and with Colorado weather being fickle, we've been snowed on multiple times. I am always freezing, I'm often unable to heat my sleeping bag because my wonderful body just doesn't produce warmth. So, I bought a heat wave pack, crack it and drop it into the bottom of my bag & it keeps me warm for at least two hours if not longer. By the time it cools I've created enough heat in the bag to keep me warm through the night.Update - 03.16.17 - I was resetting the packs as a I normally do, in a pot of boiling water and both set of seams burst and destroyed the heat pads. They were only in the water for 7 mins and I had reset them this method 20 times before. Super disappointed. I will buy to more because I need them for camping but maybe not from the same company. The smaller version I have from a different company has lasted me two years with no issue so I wonder if these two had a manufacture defect.

This is a very useful and very neat product! It works exactly as described -- click the metal disc, and the clear liquid instantly starts turning into a crystal-like product and produces nice heat for a good hour. Boil it until it's clear again, and it's ready for another round. Ingenious! Since the outside of it is ordinary plastic, I would recommend you wrap it in a towel before boiling it, to avoid having the plastic touch the sides or bottom of the pot. Otherwise, the plastic could melt. I've also found that, after boiling it, the pack stays warm for a while, so you can actually use it again when it's fresh out of the boiling water, while it's still warm -- it stays warm for a good long while. Then, once it cools, if you're ready for more, it's ready to be re-activated. Pretty neat! I'm considering buying more of these in different sizes. Excellent product -- I will be using it a lot.

Instantly gets hot. I don’t have a accurate temperature gage to list the tested temperature but it is not excessively hot to cause permanent damage from direct skin contact. However that being said when avoiding skin contact use a thin cloth to reduce the amount of heat loss from the fabric. Recharging the pack is straight forward and easy. Depending on the pack size you will want to confirm if you have a large enough pot prior to purchase.It also states it’s made in the USA and is composed of non-toxic chemicals.