The Birkenstock Unisex Zermatt Wool Slipper is Birkenstock's first true slipper — combining the brand's iconic cork-and-latex anatomical footbed with a wool felt upper and full shearling lining for serious cold-weather comfort. Made in Portugal. Versatile enough for indoor lounging or short outdoor errands. Fit notes: Birkenstock uses European sizing. EU 36 fits like a U.S. women's 5–5.5; EU 40 like a U.S. men's 7–7.5. The Zermatt has a slightly snugger fit than the open-back Boston due to the closed-toe construction. Order your regular Birkenstock size; the footbed molds to your foot over time the same way the brand's sandals do. Authentic Birkenstock, shipped from Feet Heart — authorized Birkenstock retailer. Free U.S. shipping, free returns, fit help at (310) 398-7497 from our Culver City and Arcadia stores.