Very, very comfortable! They are for small bottleI cant fit a Large size justSkinny and long botle I?m a 7 wide, they fit perfect. The inside is a faux leather and suede material and feels really nice. It is lightweight to take with you on the go and easy to operate. Note: Used outside of manufacturers intent. This is simply the best Bluetooth speaker Ive ever purchased and is unbelievably loud . They can be easily cleaned if they get dirty! The bottoms are sturdy and kept his feet from sliding on the pool deck which was great because that was the one place on the ship we went to the most. So, these babies are going back and Im just going to order the other style directly from Birkenstock.