Rear light with brake warning.

[Ming the Merciless]

I bought mine to help my son gauge what's happening when we are commuting on the bikes, not really bothered in the slightlest what car drivers think of it.

And it is significantly brighter when braking.

Do you drive a car yourself @Ming the Merciless ?

Yes, as do around 85% of people who also cycle

 

[cougie uk]

My friend has just got one with a braking function. I'm not looking at the light though - I'm just used to him getting closer when he brakes.

I doubt car drivers would ever think of brake lights being in use on bikes.