The mitts surround your hands. Here's what I'm talking about:
But there are cheaper options that are for shoulders that you can just put on or wrap around.
Also, filling a sock with rice works just as well.
I have one! It brings a TON of relief. It doesn’t last super long but it does really help. I also have microwaveable mittens I use with the bath to help keep heat longer. This is them——-> REVIX Microwavable Heating... https://www.amazon.com/dp/B0828ZJDQ9?ref=ppx_pop_mob_ap_share
If you get relief from heat I would 1000000% recommend it.
Edit to say, I like to use mine right before bed. Helps me fall asleep. Also, you can leave it on all day during a flare—I do.