BE COOL. The Nike Dri-FIT Legacy91 Hat blends breathability with sweat-wicking power to keep your head cool and dry during your workout. The back strap lets you adjust for the perfect fit. Benefits Dri-FIT Technology helps your head stay dry and comfortable. Adjustable hook-and-loop strap at the back lets you personalise the fit. Embroidered eyelets near the top let in air.