Our most-advanced XC4® yet! Exclusive breathable, seam-sealed waterproof construction and materials. Axis Chassis™ system for optimal support and stability. Smart Degree Technology® temperature-regulating interior polymers activate at both hot and cold temperatures, so your feet feel just right all day. Linings are treated with antimicrobial protection for enduring wear. XC FOAM® midsole delivers superior cushioning and ultralight comfort. Dual-width footbed can be easily removed to accommodate your own orthotic or wide foot. Removable multi-density footbed with memory-foam cushioning and arch support. Durable rubber sole.