Its an elastic fabric. I guess im too short for size m so its a little loose on the zipper zone. This item was shipped in a different package to the swimsuit i ordered but, they nicely replied to all my worried e mails and, in the end, even thought they were delivered like 3-5 days apart, they both got here by the same week. Also gifted me a pair of cute socks for the delay. Would i buy from them again? Absolutely. I dont dont if my email helped my order to be delivered more fast but, if you are a chilean buyer as me, after you pay, send them an email givin away your RUT. If they dont have it, they wont be able to send your package. I dont know how to upload the photo to the website tho!