Fieldsheer’s latest men’s and women’s Thermick Heated Baselayer Shirt is a thoughtful combination of form, function, comfort, and value. Combined with a comfortable thermal fabric, the Thermick Baselayer Shirt delivers all-day warmth while keeping you dry and protected from the elements. Powered by Powersheer with a universal USB charging port, the 7.4-Volt Lithium-Ion battery holds up to ten hours of power per charge delivering comfort no matter what nature throws at you. Fieldsheer’s Technology is integrated with multi-zone heating elements, helps maintain circulation, decreases muscle soreness, and helps regulate internal temperature. Since 1978 Fieldsheer has redefined what it means for the modern explorer, and the Thermick Baselayer Shirt is another step in that evolution. A cotton-poly blend combined with a thermal midweight layer and rib-knit cuffs and waist provides unparalleled comfort and performance, keeping you in the field and doing what you love longer.Baselayer Features:58% Cotton, 38% Rayon, 4% SpandexSweatsheer Moisture Wicking Mesh LinerThermal Midweight Base LayerIn-seam Thumb holes on cuffsRib-Knit Cuffs & WaistMulti-Zone Heat Elements: 2x BackIntegrated Touch Control Button4 Selectable Heat Settings7.4volt Rechargeable Lithium-Ion BatteryUp to 10 Hours of Power Per ChargeUniversal USB Charging InputBattery Features:Powersheer Standard Rechargeable Lithium-Ion Battery (7.4V 2200mAh)Up to 10 Hours of Power Per ChargeUL/CE certifiedUSB Cable includedCharge Time 3-4 hours*