Featuring Therm-ic heated liners and our women-specific 102mm "regular fit", the all-new PURE HEAT delivers an incredible blend of power and precision in a customizable, boot-fitter friendly design. The heated liner with Merino Wool insulation features an integrated control panel on the upper cuff to select between four settings: off, moderate (17-19hrs), medium (8-9hrs), and high (4-5hrs); batteries can be recharged using the provided USB cable.