Pop it in the freezer or put it in the microwave to give you either kind of relief that you like. When you heat it, it smells like breakfast cereal (flax seeds or rice ingredients), which the instructions say will dissipate over time.
Not a big issue really, the smell isn't bad (especially if you don't mind breakfast cereal). From the freezer the pad smells like what it is, cold (frozen) polyester.
You can add some essential or essence oils to this, on the cover, after heating it. I chose to add toasted rice & tropical sunset blends, then I sat on the porch & let the warm pad do it's thing. You can get this wet, for a moist heat, but I don't think that I would soak in the tub with it, as it could get too wet.
Everything of this pad is microwave safe, which is awesome! As with any heat & apply item. Be sure to add to the time in small numbers & feel how hot it is, to be sure that you don't get burned. It's safer to bring up the temperature slowly, than all at once.
I have an electric, over the neck heating pad, but am tethered with it. With this Sunny Bay, BioMed pad, I can walk along the deck or otherwise be untethered. The contents as well as the outer cover, hold this pad securely in place as you move about. I never felt like it was going to fall off.
I would like to see a tie, or closure for the neck, bringing it more around the collar bone, but this does just fine on the areas that it does cover. I certainly should have a larger one.