Developed by Swiss Side's aerodynamic experts, these sleeves are designed to reduce air drag to save up to 8 watts on the bike course of triathlon competitions. Suitable for all triathlete types, they offer a non-compressive aero fit for easy application and removal during transitions. Sizes : S: < 35 cm // M: 35 – 37 cm // L: >37 cm Sizing tips: For a better fit, choose one size smaller if unsure. If you have thin ankles and larger calves, go for size M for a comfortable and secure fit.