Balls hold heat very well as long as you have a good lightbulb. The bulbs (I have 2) that come with the product are great but not very durable. 15W bulbs do a good job of heating the balls, but I've found 25W or more to work better. My husband has a lot of breathing problems and the salt stones helped him a lot. This is a bonus as you can pick them up and throw them at the sore spots. I woke up one night with a spasm so bad I thought I had to go to the hospital and my husband rolled one of the balls over it and it went away in a few minutes.
6" E-book Amazon Kindle 10 2019-2020 8 GB 800x600, E-Ink, 8 GB, black
26 Review
6" E-book Amazon Kindle PaperWhite 2018 8Gb 1440x1080, E-Ink, 8 GB, twilight blue
59 Review
6" E-book Amazon Kindle 10 2019-2020 8 GB 800x600, E-Ink, 8 GB, white
36 Review
LED strip Yeelight LED Lightstrip 1S YLDD05YL, 2 m, LEDs: 48 pcs., 7.5 W, multi-colored, version: Rostest (EAC)
23 Review
LG G7 ThinQ Poetic Guardian Series Case - Hybrid Shockproof Bumper Clear Cover With Tempered Glass, Blue
22 Review
ZOUTOG 60-Pack 4 Inch Round Biodegradable Peat Pots For Seed Starting In Garden, Greenhouse, Or Nursery With Bonus Plant Labels
29 Review
Surace Compatible With Apple Watch Case 38Mm For Apple Watch Series 6/5/4/3/2/1, Bling Cases With Over 200 Crystal Diamond Protective Cover Bumper For 38Mm 40Mm 42Mm 44Mm (38Mm, Clear)
21 Review
45Mm 41Mm 40Mm 38Mm 44Mm 42Mm 49Mm Compatible Silicone Sport Bands For Apple Watch Series 8 7 6 5 4 3 2 1 SE, Maledan 6 Pack Breathable Strap Design Women Men Ultra IWatch Band
26 Review