This was a prototype I made a while ago. It's a handmade item by an amateur. The waist is fully elastic, and flat measurement is about 31-42cm, adjustable with a drawstring. I used to wear it as loungewear in the summer, but I stopped wearing it after I started wearing other things. It's made of sturdy 100% cotton fabric. Please feel free to comment if you have any other questions. Thank you for looking.