I wonder what pair of upside down Birkenstock sandals this shot is of? Makes no difference really, what you’re seeing here is consistent among all Birkenstock footwear. Cork, jute, and non-abrasive glue, and eva. The good stuff that makes up the quality footwear that will last you generations. Seen here in black and white with a little dramatic lighting makes for a neat shot!
Tread Lightly,
Aaron