Defy the cold and stay productive with the FrostFlex Heated Vest. Designed for frigid environments, this battery-powered vest delivers core warmth without bulk. It works alone or zips under the 8300 FrostFlex Insulated Jacket for extra defense. With three heat settings, an 8-hour runtime, stretch fabric, and water-repellent finish, this vest helps you stay warm, mobile, and focused when the temperature drops. Sizing Instructions: For the most accurate fit, take your measurements over the base layer of clothing you intend to wear with this RefrigiWear gear (such as thermal underwear, jeans or a sweatshirt) and refer to the size chart for this product.