Using these UV Sunstop Arm Covers is a breeze. Simply slide them onto your arms before you head out for a cycling ride. They are flexible and stretchy, so they should fit most arm sizes easily. As for precautions, avoid sharp objects that could tear the fabric. When it's time for cleaning, hand - wash them in cold water with mild detergent. After washing, let them air dry. Don't put them in the dryer as high heat may damage the fabric and reduce its sun - blocking ability. With proper use and care, these arm covers will serve you well for many cycling trips.