If your aches and pains go beyond what a cuddling a microwavable plush sloth can soothe, a good heating pad is a must. But with dozens of brands to choose from at your local pharmacy and online, which one should you get?

After a recent trial run, the answer here at Mental Floss HQ is clear: the Sunbeam king-size moist/dry heating pad massively outperforms its $15 price tag. The giant heating pad gives high-end pain-relief gadgets (many of which we also love) a run for their money, with three different heat settings, a moist-heat option, and auto shut-off. Most importantly, it's big—at 11.7-inches-by-8.1-inches, it's made to stretch across your whole back, abdomen, or hips, meaning that it can target entire muscle groups at one time.

Sunbeam, Walmart

Though you can use it as a standard, dry heating pad, it also comes with a sponge insert that you wet for more penetrating heat. Studies have shown that heat therapy can help reduce muscle tension, increase circulation, and relieve pain in numerous different contexts, from chronic lower back pain to jaw pain [PDF] to muscle soreness from exercise. Some studies have also found that applying moist heat is more effective for pain relief (though others have noted no difference, although patients often prefer moist heat).

I bought the Sunbeam pad to soothe my chronic back and shoulder pain, and quickly found that I wasn't the only evangelist for the product. When I posted on Instagram about my new purchase, a friend immediately messaged me: "using mine right now … and ohhhh it is so good." She was right. It's so good.

One more testament to its greatness? It's so popular that it recently sold out on Amazon. Luckily, you can still find it at Walmart or at one of the retailers below—but grab it before it sells out there, too.

And yes, it's FSA eligible.