100% Polyester Four-way mechanical stretch Vertical venting at the back and chest SPF factory of 30+ Wicking properties Fast drying, virtually wrinkle-free Great news! The TekCheck is available in new colorways and a Long Sleeve and a Ladies' version. This versatile shirt puts added flex in your days, as it is made using MicorFiber with Mechanical Stretch to give you a freer range of motion at work or play. Though we've updated the colors and expanded the style selection, one thing you can count on is these shirts offering the same great styling as our top-selling MicroFibers - vertical venting with mesh lining at chest and back, UPF 30+ protection, and a printed inner label.