Chill-Its 6225 Premium FR Phase Change Cooling Vest keeps workers cooler, safer and more productive, maintaining a 64-degree Fahrenheit (18-degree Celsius) temperature for up to 4 hours when activated. Pair with cooling charge packs (not included) that quickly recharge in 10 minutes and have patented honeycomb design to eliminate stiffness. Extended vest surface area enhances cooling power. Flame-resistant vest is made of a modacrylic, cotton blend, FR fabric that meets ASTM F1506 requirements as well as being classified to NFPA (CAT1). Adjustable hook-and-loop closures at the shoulders and waist provide a customized, comfortable fit. Reflective accents mean more visibility on busy streets or jobsites. Two pen slots on the right side of the vest keep your writing utensils handy. This body cooling vest delivers instant cooling relief for anyone working or playing outside or indoors in warm temperatures where heat-related illnesses are possible. This size fits 40″ to 52″ chests.