From The North Face, the Women's Thermoball Traction Leather Mule Slip Ons feature: Leather upper from Leather Working Group–certified tanneries Oso fleece collar lining for added comfort Fleece lining for warmth Lightweight and packable Slip on with collapsible heel with elastic side panels for easy on/off THERMOBALL™ 100% recycled polyester insulation helps keep feet warm even when wet Outsole made with up to 20% recycled rubber Imported.