longer length plus breathability. the nike tempo 18cm boys' running shorts were built for comfort and coverage, with sweat-wicking fabric and a generous inseam.. benefits. dri-fit fabric to wick away sweat and help keep you dry and comfortable. elastane for a comfortable, conforming fit. side-seam pockets for convenient small-item storage. product details. 18cm inseam based on size medium. fabric: body: dri-fit 90% polyester/10% elastane. mesh/briefs: dri-fit 100% polyester.. machine wash.