This "Just Like a Kotatsu" series, using patented technology to warm you from the feet up, is designed for sleeping. Addressing the worries of cold feet preventing sleep and the anxiety of needing to sleep, it offers three sleep-inducing features to warm your feet and envelop you in a cozy, kotatsu-like warmth. 【For Cold Prevention During Sleep】It thoroughly covers the soles of your feet, where blood vessels are concentrated, warming them all the way to your toes. The open-toe design allows for comfortable use during sleep without causing your feet to sweat.