Description:  OPTICAL DESIGN AND GIFT IDEA:  The optical design is applied to this bike tire light, and it makes the light illuminate whole tire rim brightly but softly to protect your eyes, especially the children. These bright bicycle wheel lights will be the perfect Birthday presents, Burning Man, Christmas gifts for kids, boys, girls, teenagers, adults of all ages! SMART VIBRATION SENSOR:  Whenever daytime or night, after turn on the bike light for wheels manually, the motion sensor can detect riding state/vibration to turn the light on automatically or turn off after staying motionless for 30 seconds. Compared with others, it is even better in energy conservation and environmental protection.  EASY TO INSTALL AND NO ADDITIONAL RESISTANCE:  Just need few steps to put it on the bicycle hub and no tool needed. The light is placed in the center of the wheel so it will not affect your safe cycling. Cool bike accessories for Kids' balance bikes, boys bikes, girls bikes, road bikes, mountain bikes, wheelchair, etc. With the bicycle lights, your bike will stand out from all angles!   Brand Name: STEVVEX SportModel Number: ST90SP0124RGI   Mounting Placement: Wheel SpokesPower Supply: BatteryMaterial: PCFunction: constant lighting, flashApplicable: Kids balance bike, Mountain bikeInstallation diameter: Less than 39mmBattery capacity: 300-350mAh Li BatteryWork time: 8-12 hoursWaterproof rating: Life waterproof