Sleeves like these Assos armProtectors are ideal protection on hot days. For some it is anathema to summer. My Vitamin D! But when you have to protect your skin, a summer sleeve is the way to go. These armProtectors are closer to 'coolers' than they are to 'warmers,' as they're so thin you'll have a hard time noticing any change from bare skin unless you're riding in super high humidity. They have simple welded grippers to hold them to your upper arms, even when you sweat. They're light and give you effective UV protection no need for chemical sunscreen all the way down to your wrists. The Assos armProtectors come in Black and White. There are three sizes 0, I, and II.