Manufacturer: Okamoto Color: Grey Material: Acrylic, Wool, Other Size: 23-25cm Recommended for those who can't sleep due to cold feet! These socks for sleeping warm your toes and help you get a good night's sleep. The double-layered heat-generating material warms the soles of your feet and promotes blood circulation. The unique design with open toes lowers your core body temperature for a better sleep. The heat-generating material on the heel stimulates pressure points, leading to relaxation. These are sleep socks from the "Marude Kotatsu" (Like a Kotatsu) series, which warms your body from your feet with patented technology. For those who can't sleep due to cold feet or are anxious about not being able to sleep, these socks have three sleep-inducing features to warm your feet and provide a cozy, kotatsu-like warmth. [For Cold Prevention While Sleeping] They cover the soles of your feet, where blood vessels are concentrated, and warm your feet all the way to the toes. The open-toe design allows for comfortable use while sleeping without making your feet stuffy.