Spidi Airtech Armor is a summer jacket made with high tenacity mesh that combines technical features of a racing jacket to those of urban mobility. It's studied to be worn by itself or under a second-layer shield. Technical features: High tenacity mesh outer fabric. Forcetech protections certified EN 1621-1 on shoulders and elbows. Ready for Warrior back protector certified EN 1621-2 Level 1 and Level 2. Ready for Warrior Chest and Thorax Warrior prEN 1621-3 certified. YKK® zippers on front and pockets. Velcro adjustment on the sides and arms. Two front pockets. Each size covers two sizes, so there is no M size. So the M fits the S.