Birkenstock® Size and Width Chart Please be advised that the Birkenstock® Narrow width accommodates both traditional narrow and medium widths. Spring and summer demand a great sandal like the Mayari from Birkenstock®. Premium leather or Birko-flor™ upper with adjustable buckle closures to ensure easy on-and-off wear and a secure fit. Birki-flor is made of acrylic and polyamide felt fibers. See drop down color menu for materials. Birkenstock uses the color names Antique Lace Birko-Flor and Graceful Pearl White interchangeably and boxes may arrive marked as either. Anatomically correct cork footbed, crafted from cork that is 100% renewable and sustainable, encourages foot health. The suede lined, contoured footbed will mold to the shape of your foot creating a custom footbed that supports an.