Using your Serfas bar end mirror is easy. First, find a suitable handlebar with a diameter between 16mm and 22mm. Then, use a 5mm hex wrench to attach the mirror to the bar end, applying a torque of 1 lb/ft (12 kg/cm). You can adjust the mirror to rotate 360 degrees to get the best view of your surroundings, and it works on both the left and right sides. When it comes to maintenance, simply wipe the anti - glare glass lens with a soft, dry cloth to keep it clean. Avoid using abrasive materials that could scratch the lens. Also, check the tightness of the mirror regularly to ensure it stays in place while you ride.