The NiteRider Sentry Aero 260 keeps guard both night and day with an aerodynamic shape that gives cyclists 260 degrees of visibility with a matching 260 lumens of light output featuring Optimal VIZ Daylight Visible Flash (DVF) technology. It's lightweight form factor (65g) and ability to fit standard to aero seat posts makes this light the perfect choice for Triathletes and Road Bikers alike.Innovative Aero shape with excellent side visibilityUltra Bright Daylight Visible 260 Lumen Flash ModeGroup Ride Mode - Be Seen Without Annoying Fellow Cyclists2 Light Levels plus 2 Flash Modes