Nice hat for sunlounging, it will make an interesting array of diamond shadows in the sunshine. It has an inside diameter of 17.5cm, outside diameter is 46cm roughly. it has gentle ergonomic fit, is breatheable, has a geodesic sphere inside inspired by radar domes. I can custom tailor one of these in a regular/long oval standard hat, If you want one of these and perhaps even a set of of hats for a catwalk, please contact me here. Thanks!