The Niterider Sentinel keeps a watchful eye over the night projecting highly visible laser lines for your own personal bike lane, enhancing your safety immeasurably, while also giving you protection during the day with Daylight Visible Flash (DVF) technology.Optimal VIZ with Daylight Visible Flash (DVF) A wearable safety light clip onto various straps, belt loops, etc. Highly visible laser lanesGroup Ride Mode be seen without distracting fellow cyclistsEasy on and off seat post strap mount with quick release tabConvenient USB rechargeableWhen powering off, center circle will light up red indicating low battery FL1 Standard IP64, dust and water-resistantItem SpecificationsBatteryLi IonLumens Rear250Recharge TypeUSBWeight116 NiteRider Sentinel 250 Taillight Taillight UPC: 702699050891