Best For: Training The TrailTrainer Fleece Zip-T is the ultimate mid-layer for field training—warmth without the bulk. Built with the same advanced fabric as the KUIU Vital S3 and purpose-tuned for high-output training, it delivers comfort that moves with you on runs, hikes, and rucks. Wear it alone in cool conditions or layer it under your favorite shell. The 127 g/m² fabric combines moisture-wicking, quick-drying performance with XLANCE® stretch technology: a stretch yarn that resists sweat, chemicals, heat, ozone, and UV while staying incredibly light. Unlike traditional elastane, XLANCE offers gentle, low-force stretch that feels fatigue-free during dynamic movement yet recovers season after season. Toray Makspec® antimicrobial treatment keeps odor at bay. Half-zip ventilation, raglan sleeves, underarm panels, and a drop-back hem complete a mid-layer that stays dry and ready for whatever the day demands.