The ultimate baselayer for protection against extreme cold, the ULTIMATE offers three main benefits: Your body heat is sealed in like a standard baselayer Unlike a standard baselayer the product instantly warms you up Unlike a standard baselayer the unique fibres Garment Construction: acrylic 68%, nylon 21%, polyester 2%, wool 7% & polyurethane 2% The unique fibres on the inside of the Ultimate rub against your skin to create frictional heat Unique fibres The heat rub uses ‘double-loop’ barrel fabric which provides both heat insulation and ‘friction heating’. The extra-long bristles ensure a layer of warm air is retained around the neck and even a little movement of these bristles causes friction which creates heat and actually warmers you up. The Heat rub is twice as warm as a jumper and is comparable to a coat but with the ability of ease of movement for active sports and working. Sizing Guide To fit Chest Inches S 32-36 M 36-40 L 40-44 XL 44-48 XXL 48-52 Sizing note The above sizing shows optimum chest sizes however due to the unique stretchabilty of ZF you will be able to fit into a higher selection of the above sizes than would be traditional.