They are very versatile. If heated in the microwave or in the oven (or simply kept on the heating for a while) they're very good for rheumatic pain or the likes. If kept in the freezer for a couple of hours, they're very good for insect bites or inflamed body parts. I used one after my arm got swollen and inflamed after the second Covid jab and it brought everything down within the week.

Basically, they're used as cold or warm packs. And since they are only loosely filled, they can adapt to the shape of the body part nicely. I kept mine under the sleeve of my t-shirt for 15 minutes a time and it remained on my upper arm without sliding down.