The Sala studded shoes are a lightweight and high-quality option for cold winter days. The lining material contains 70% recycled wool, which helps keep you warm and also naturally reduces odor issues. Sala is a membrane-free and breathable modelthese shoes are not waterproof and are best suited for dry conditions. The zipper at the front makes them easy to put on and take off. Icebug refers to the studs as "intelligent studs" or "dynamic studs." This means that on hard surfaces, the studs can slightly retract into the sole, allowing the rubber material to make better contact with the surface. Note! This feature does not make the studs safe for sensitive flooring. - Wide Icebug fit - BUGrip sole with 17 "intelligent studs" - Shock-absorbing midsole (EVA foam) contains 20% BLOOM foam, made from algae collected from overgrown lakes (for once, truly algae-based action!) - Upper fabrics are ripstop polyester with bluesign and GRS certification, made from recycled PET plastic bottles