The North Face Thermoball Traction Mule V Color Purple Size 7 NWOT Post-expedition comfort should never be an afterthought. That’s why we created one of our most iconic styles—the THERMOBALL™ Traction Mules. As the original off-grid slip-ons, these warm, durable shoes were born at base camp but adapted for everyday life. Lightweight and packable for easy transportation. Insulated and fleece-lined for unrivaled comfort and warmth. These are the all-in-one solutions for running errands, après relaxation or kicking back at camp.