Knit-in ventilation Ergonomic design Thumbholes at cuffs help keep sleeves in place Slim fit This Dri-FIT Knit Long Sleeve Running Top from Nike keeps you warm and cool when you need to be. A design that keeps up with you and your workout, with knit-in mesh for enhanced breathability and ventilation to keep you cool and keep you going. Thumbholes keep your hands warm when the temperature drops and the ergonomic design allows greater mobility when training.