Mountain Hardwear Super Power Arm Warmer Along the arms is a high-visibility print that helps keep you visible at night. The Super Power Arm Warmers were constructed with a flat-lock seam to eliminate chaffing. These arm warmers are crafted with Basso Jersey, which is a blend of polyester and elastane. The Mountain Hardwear Unisex Super Power Arm Warmers are a lightweight pair of arm warmers that keep you protected from the cold and wind while out on the trails. The ultra-stretchy fabric is fast drying and provides a snug fit sure to stay in place.