Review on Stay Safe While Cycling With G Keni Smart Bike Tail Light - Auto On/Off, Waterproof, USB Rechargeable, And Ultra Bright LED Warning Back Bicycle Flashlight! by Jeff Remol

This light has four modes. if you use Flash or Breathe (pulse) the light will auto off in 30 seconds.If you use strobe or always on, the light does not auto off in 30 seconds, it just stays on.I prefer to leave the light on all the time, so it will not auto off if I'm not moving.The auto off feature is awesome, if the light stops moving for 30 seconds it turns off.Any movement turns it right back on instantly. I kind of like it, just turn it on and forget about it.The brake light is the feature I purchased this for. Cars ride close and I want them to know I'm on the brakes.This brake light lets others know I'm hitting the brakes. It's automatic so any decent deceleration will trigger it.I'm not sure about the clamp feature, I use the rubber band and it's very secure.If you need brake lights click buy, this is a great compact light.