Black Birkenstock Double Buckle Sandals Sz 39N

Stylish black Birkenstock sandals with double buckle design. Comfortable and versatile. Bought on posh as leather but truly not sure. They feel like leather and look like leather. Love them but I’ll need a size 40. Lots of tread, some signs of discoloration on black and interior markings has worn off but Birkenstock imprint info is visible, they have been cleaned.