I used these for about a month after purchase. I think there are no noticeable stains. The size is 23.5cm. These are easy to wear and provide comfortable steps: Skechers Hands Free Slip-ins: Ultra Flex 3.0 - Natural Step. They feature a unique Heel Pillow in the heel. This laceless style combines an upper made with Stretch Fit engineered knit and a leopard print with a Skechers Slip-ins molded heel panel. They are equipped with a cushioned Air Cooled Memory Foam insole. ■ Machine washable ≪Function Information≫ ・Skechers Hands Free Slip-ins fit your feet immediately ・Unique Heel Pillow securely holds your feet ・Cushioned Skechers Air-Cooled Memory Foam comfort insole ・Sock-like comfortable Stretch Fit design ・Made with 100% vegan materials