SockGuy Acrylic Grey Cycling/Running/Hiking Arm Warmers (S/M) Micro-denier acrylic or Isowool(50% Merino wool50% Polypropylene) blend regulate temperature and wick moisture Arm cuffs keep warmers in place Articulated elbow prevents bunching Wide elasticized wrist cuff stays in place Softest arm warmers in the industry