CALM, CASUAL AND COLLECTED. The Nike Sportswear Tracksuit is made with smooth, stretchy knit fabric ready for everyday wear. This updated style features a clean, tailored fit and piping details that help to highlight the sport-inspired design. All-Day Comfort Poly-knit fabric is lightly brushed on the back, making it soft and smooth for all-day wear. Two-Piece, By Design this versatile top to bottom fit updates a classic to help keep your look casual and clean. Secure Fit. Clean Lines an elastic waistband with drawcord stretches for comfort, and elastic cuffs let you show off your kicks. Piping at the shoulders, sleeves and sides highlights the clean lines.