- 3.8-ounce, 100% polyester flat back mesh with PosiCharge technology - Tag-free label - Moisture-wicking - Flat knit collar - Taped neck - 3-button placket with dyed-to-match buttons - Set-in, open hem sleeves To view the sizing spec sheets for this polo visit www.sanmar.com. Type "YST640" in the Product Search Box.