fra110564412wrote a review of Castelli Thermoflex Arm Warmer on December 8, 2017
Fit: Runs small
I am 6'0" 190 lbs with average size arms. I first ordered the L and could barely get it on. It was even tight on my wife, who weighs 125 lbs. I then tried the XL which was still tight on me. I'd think Castelli could give biceps size in their sizing chart, everything else is a waste of time. If you order anything from Castelli, from my experience with their products, order up at least TWO sizes from your usual size, and keep your fingers crossed.