You insulate the rest of your body with drywear and wetsuits; don't forget your head. The NRS® Storm Cap, with its 2.5 mm neoprene, provides excellent thermal protection. Warm, insulating neoprene Titanium-laminate adhesive reflects back body heat to increase warmth Flat-locked, taped seams help keep water out and warmth in Quick-drying Checked VaporLoft™ lining for extra warmth and comfort Sturdy, flexible bill provides shade from the sun and helps keep water from dripping into your eyes Stretchy, comfortable no-buckle chin strap makes the cap easy to put on, even when wearing gloves Ear vents Weight: 3 oz. Color: Charcoal Unisex Size Chart: Small: 51 - 55 (cm), 20 - 21.5 (inches) Medium: 55 - 58 (cm), 21.5 - 23 (inches) Large: 58 - 62 (cm), 23 - 24.5 (inches) Fit tip: Measure head circumference. If you plan to wear the Storm Cap under a helmet, the thicker neoprene may require you to go to a larger size helmet. Style Number: NRS15046.01.100, NRS15046.01.101 NRS Storm Cap