Soothing and relaxing [SEP] These rocks have helped me so much. I have a chronic hip and back problem and arthritis as well. I have been hobbling around for weeks , even after physical therapy. I used these once and was 80 percent better after the first usage. They are beautifully presented in the clam shell . They get hot enough after 12 to 14 mins. They stay warm for about 10 to 15 mins , which is a bit of a disappointment but they warm fast if you want longer treatment or to just leave them on your body until they cool. Very soothing.