Can we make an aero sock, that is first and foremost a really good sock?  Josh worked with a team in Italy who is quite famous for making the finest socks in the world, and who also has some of the most modern kitting machinery in the world.  The goal was to make a knit sock that won't fall down, but has a combination of smooth and rough texture to trick the air into flowing around the lower leg more efficiently.  The result is a sock which matches the aerodynamic performance of ribbed lycra cuff socks, while retaining all of the features you demand from a cycling sock. After discovering the true gains to be had in aero socks we released our every day aero sock.  We got tons of great feedback on how comfortable they were but many asking for a sock that could push the UCI limit and be even more aero.  We extended the cuff to 19.5cm to be right on the UCI limit for most riders. The technology: Custom knitting machinery allows us to produce a sock with smooth frontal surface where the airflow is laminar, with the addition of 3 rows of turbulators starting just ahead of the flow separation zone.  These turbulators introduce small vortices in the boundary layer which energize the flow and promote flow attachment further around the leg.  More attached flow means a smaller pressure wake behind the leg, less wake = less drag.  4-8 watts drag reduction when compared to standard sock and equal to ribbed lycra socks of similar height SILCA aero socks are knit from Q-Skin, a silver ion infused polyamide which is anti-bacterial, odor resistant, and more importantly, has better softness and moisture control than any of the yarns commonly used to knit socks.  Not only are these socks fast, they're the most comfortable sock you've ever worn. Socks are not eligible for returns once tried on.  Please refer to our sizing guide below for best fit. Sizing (based on EU shoe size)S 35-37      M 38-41       L 42-44        XL 45-48