These PolarForce Insulated Bib Overalls were made for moving. Designed to keep you productive and your performance high with Performance-Flex and abrasion-resistance, you won t be held back from peak performance. The new Performance-Flex feature on the knees and side waist keeps these -40°F Comfort Rated winter overalls flexible so movement isn t hindered. Earn the Mvp award and get home safe – all while being protected from the cold and looking good to boot. 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.