The comfort material is made of urethane foam, covered with (cloth) nylon webbing. On selected models Dry-Cool® liner material is used, that dries extremely fast and disperses transpiration and heat much faster than conventional liners. In combination with the inner shell, the inner liner provides a snug and comfortable fit, which is of course important for the performance. The luxurious absorbent liner breathes and disperses moisture. The entire interior is washable in place, just clean with mild soap and lukewarm water, rinse well and let it dry for a day, never in direct sunlight or near a stove. Several Arai models feature complete or partly removable interiors. These may also be cleaned and washed, just place them in the washing machine. Different size thicknesses are available to fit those in-between sizes for a custom fit for every rider. CHARACTERISTICS OF SHELL MATERIALS Any good raw material is just simply “raw material” unless technology is provided to make it suitable for the specific needs of helmet shells. Fibreglass Good for extension, compression, good balance for overall strength and reliability, but heavy. Its density is about 2.4 specific gravity. Kevlar Good strength in extension, very light, specific gravity is 1.4. Strength for extension is more than steel, but not good enough against compression (as compared to fibreglass) and cannot be used solely as shell material.
Carbon fibre Specific gravity is 1.8. Very strong after moulding, needs very careful manufacturing process for best results. Very hard surface, high resistance against abrasion. Obligatory outer shell material for Formula One helmets according to FIA regulations. Super Glass Fibre Originally developed for space technology and army defence purposes. Specific gravity is 2.4, about the same as fibreglass, but up to 40% stronger for extension and bending resistance than normal fibreglass.