With our pro riders we set out to make a better seamless arm warmer. Others on the market are made with a nylon/Lycra® blend that tends to hold moisture, but we knew we could get better moisture management with a polyester yarn. Working with polyester makes it more difficult to get the right stretch, return and manufacturing consistency, though. It took a year longer than we thought, but we're all glad we stuck with it. These warmers are a pro rider favorite because they're crazy light and they're extremely warm for their weight, yet even in milder conditions you don't overheat. They're so stretchy you hardly feel them on, yet when you take them off they occupy a fraction of the space that normal warmers would take in your pocket.