Sport-Tek PosiCharge Competitor Polo. ST550Our #1 performance tee fabric offered in a color-locking, moisture-wicking polo to expand your uniforming options., 3.8-ounce, 100% polyester interlock with PosiCharge technology, Flat knit collar, Removable tag for comfort and relabeling, Taped neck, 3-button placket with dyed-to-match buttons, Set-in, open hem sleeves, Due to the nature of 100% polyesterperformance fabrics, special care must be taken throughout the printing process.