Be seen either in the day or at night with the super-powerful Flux Expert tail light. The flashing mode automatically boosts the lights output to 110 lumens during the day for up to 14 hours while making you visible up to a two thirds-of-a-mile &40;or one kilometer&41; in full daylight. Maximum safety even in the brightest conditions. 110 lumens output sets new benchmark. Visible up to 0.6 mile/1.0 kilometer during midday in the summer. Patent-pending reflector mounting system for perfect aim on 27.2 30.9mm & Venge seatposts. Ambient light sensor boosts light output by 50% while in Flash Mode during daytime running for increased visibility. Integrated flip-out USB (Universal Serial Bus) tab to charge rechargeable Li-Ion battery in any USB (Universal Serial Bus) port in under 90 minutes. All the aesthetics & performance to match the fastest road race adventure & commuting bikes. Three operating modes: Steady 25 Lumens Surge 5-55 Lumens Flash 55-110 Lumens