With Team Ineos Castelli 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 they knew they 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 Castelli thought, but they??¢re all glad they 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.