The Harkila Heat USB-C Long Sleeve Shirt is a base-layer with genuine warmth technology built in. Three integrated heat panels - lower chest, upper back and lower back - deliver targeted warmth to the core via a simple chest button, with a USB-C power bank supplying the energy. Full-stretch fabric ensures unrestricted movement whether you're active or standing still, and thumbholes keep the sleeves in place beneath gloves or mid-layers. A moisture-wicking, quick-dry construction keeps you comfortable as conditions change, making this a genuine layering tool for anyone spending extended time outdoors in cold weather. Key Features & Benefits Crew neck - clean, comfortable base-layer fit 3 heat panels: lower chest, upper back and lower back - targeted warmth to the core in extreme cold Power button on chest for easy access - simple, one-handed heat control even in gloves Thumbholes - keeps sleeves in position under gloves and outer layers Full stretch - unrestricted movement at the base layer for all levels of activity Heat Control - adjustable targeted warmth via integrated heating panels Moisture wicking - keeps the skin dry as conditions and exertion levels change Quick Dry - fast recovery when body temperature rises Stretch - unrestricted comfort across the full range of movement Ideal For Cold-weather outdoor days when additional warmth at the base layer is needed without adding bulk - particularly effective for static outdoor work or extended periods in exposed conditions. Why We Love It Easy, dependable and built for everyday life outdoors - a base layer that earns its place in cold conditions and genuinely makes a difference when the temperature drops. Wash & Care Do not dry clean. Do not bleach. Do not iron. Wash at 40°C gentle cycle. Do not tumble dry. Shut off power immediately in case of discomfort. Do not use pins. Do not use if wet. Do not dispose with household waste. Close zip before wash. Size: XS - Chest 90cm (35"), S - Chest 94-98cm (37-39"), M - Chest 98-102cm (39-40"), L - Chest 106cm (42"), XL - Chest 110-114cm (43-45"), 2XL - Chest 114-118cm (45-46"), 3XL - Chest 122-126cm (48-50"), 4XL - Chest 126-130cm (50-51"), 5XL - Chest 134-138cm (53-54")