It's time to take off the layers and bring on the short sleeves! The Flex Tee ($27-$46) from Moving Comfort is a joy to run in on sunny springtime afternoons. The seamless fabric is so soft and does a wonderful job wicking away the sweat. The shirt is fitted but not too tight. I like that it is generous in length and that the band at the bottom prevents the shirt from riding up. Plus it comes in fun colors to celebrate the season.