LONG-LASTING COLD PROTECTION - Developed with Hotronic's advanced foot-warming technology, the XLP PFI 50 Classic Comfort heat socks deliver extended warmth in cold conditions & soft compression while maintaining a lightweight feel; Compatible with Hotronic XLP heating elements (sold separately), these cold-weather socks integrate easily as a backup or alternate pair in your winter gear lineup TEMPERATURE-REGULATING MERINO WOOL BLEND - Crafted from a high-performance Merino wool blend, these unisex ski socks regulate foot temperature and enhance overall foot climate; Soft, breathable, and moisture-wicking, Merino wool keeps feet dry and comfortable during long hours in cold or variable conditions HEAT-OPTIMIZED DESIGN - These cold-weather sports socks feature integrated Classic heating zones that concentrate warmth directly beneath the toes and ball of the foot, delivering focused heat coverage when paired with compatible heating elements; The double-cuff construction provides a secure, stable fixing area for the heating system, helping maintain fit & comfort SOFT COMPRESSION RATING - Engineered with Power Fit Technology, Hotronic XLP PFI 50 Heated Socks provide light, smooth compression (10-15 mmHg) that supports circulation without restriction; The Power Fit Index of 50 ensures gradual pressure distribution, enhancing comfort, reducing foot fatigue, and improving overall fit ENHANCED STABILITY, SUPPORT & COMFORT - Added shin protection improves comfort inside tall or rigid boots; The pre-installed wire hugs the leg snugly, keeping the sock in place, while an anatomically contoured shape and thick construction deliver stability, support, and controlled compression for winter wear