Product Condition: Unused, no accessories Estimated heat retention time: For types with a capacity of 1.0 liters or more of hot water, it's about 5-9 hours when used in a futon, and about 2-5 hours when used in a room. (※The duration varies depending on room temperature and the amount of hot water). Size: Unknown I usually wear 26.5cm, but these were too small. Length of the sole: 26cm Accessories: None I received these unused, but I don't know how to use them. Since there are no accessories, are there any users out there who might be interested?