But its flexible rubber. First, the straps will loosten. I saw another co-worker wearing these one day and he stated once you try them you wont go back. Oh ALSO! I am usually a hotbox at night, but I didn’t sweat at all in these! Purchased this adorable hat for a cruise and it was perfect. Some mention there is no difference between the two but I think there is. Hopefully this informations helps someone. Thankfully I have plenty. I’d been suffering from Metatarsalargia.