I really like these arm liners. I ordered along my typical jersey/short size, and they fit perfectly, and are snug. Made of a white lycra, they can cover bare skin for a cool ride and function as a arm warmer. But their real benefit is to cover your arms on a warm day and avoid sunscreen and sunscreen issues. I've worn these on warm rides (80-85F) without too much discomfort. You could always douse them with a little water (not electrolyte) for the evaporative effect. I'll order more when I need them.