The EarthBae Chill Liquid Cooling Vest cools by conduction, drawing heat directly off your core through contact. Fill the reservoir with water and an ice pack. A battery-powered pump circulates the chilled water through tubing routed across the vest, front and back. Heat moves from your body into the water and away. Conduction works by contact, so it holds its output when the air is still, when the humidity is high, and when you are standing in one place. Between uses, the ice pack goes back in the freezer. HOW IT RUNS The pump runs on the EarthBae 7.4V USB-A battery for 7 hours per charge. One button on the upper left chest starts circulation. That is the same 7.4V standard powering EarthBae Core, EarthBae Heat, and EarthBae Air, so one charging setup covers the full system. FIT AND CONSTRUCTION Sleeveless and unisex in charcoal grey, with a collarless V-neck and a relaxed utility cut. WHEN TO WEAR IT EarthBae Chill is built for sustained static heat. The afternoon soccer game. The hot errand run at 2 PM. The summer vacation in August. The outdoor event where you are on your feet and going nowhere. EarthBae Air is the companion piece for heat with movement, where fan convection has airflow to work with. Two mechanisms, one battery, the hot half of the year covered. WHAT SHIPS The vest and the 7.4V battery ship as coordinated separate parcels and arrive near each other. The battery is included with the vest and is not sold separately. END OF LIFE When the battery finally stops holding charge, EcoDispose takes it back. Free, prepaid, mail-in, no purchase required, and it accepts any 7.4V apparel battery regardless of the brand on it. Active thermal regulation is one battery and every climate. EarthBae Chill is the conduction half of it.