Nathan Light Spur Quickly and securely attaches to heel of your shoe Super lightweight so you don't feel a thing Multi-settings for high visibility and added safety Waterproof so you can run longer in any weather Easily replaceable watch battery offers 100+ hours of illumination Usage Instructions: Press and hold power button for 2-3 seconds to turn on. Press again to switch between steady and strobe modes. Press and hold power button for 2-3 seconds to turn off.