Ergodyne - EGO41706 Designed as a mid-layer over base layers and under jackets, the N-Ferno 6495 Rechargeable Heated Vest delivers adjustable heat up to 9 hours with three heat seatings and four heating zones around the neck collar, mid-back and left and right chest for all-day warmth in cold to extreme conditions. Battery power bank (7.2v/5000mAh) with auto shutoff fully recharges in 4 hours and comes with a USB-C charging cord. Lightweight vest also offers 80g of insulation that traps body heat. It fits comfortably under bulky winter jackets and gear. Wind-resistant, quilted polyester exterior provides protection from the elements. Fleece lining around the collar adds warmth for all-day use. Stretchable spandex blend on the sides ensures comfortable fit. Elastic bungee waist with a snug, adjustable fit keeps cold air out. Zippered closure allows easy on/off. Vest is machine-washable when you remove battery pack. It fits chests up to 49.5" and waists up to 51.5" in diameter. Center back is 28" long.