Cycling arm warmers are fairly simple in nature, so it's the little details that make them comfortable and effective. A good example are these Gore Arm Warmers, which have flat-lock seams for a soft feel against the skin, pre-shaped elbows to maximize comfort and mobility, and wide elastic cuffs for a secure fit. They're ideal when you need a little bit of extra warmth on your morning ride, and can be easily removed and stuffed into a jersey pocket if they're no longer needed.