Sport-Tek® Contrast PosiCharge® Tough Polo?. ST620. Smooth, durable and made to perform, this moisture-wicking, snag-resistant polo has earned its tough reputation. 4.7-ounce, 100% polyester jersey with PosiCharge technology Self-fabric collar Tag-free label Contrast tech taping at center back neck 3-button placket with dyed-to-match rubber buttons Set-in, open hem sleeves Contrast tech taping at sides