#Silca Aero Socks feature 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. All of this good for 5-10w savings. Besides tire pressure it might be the most afforable marginal gain.
Photo: @fudgelump