Planet Bike super flash ,1w is a proper see by LED headlight, with a blinking mode.
http://www.bikeman.com/LT3044.html
1/2 w is a be seen light , with of course a longer battery run time.
http://www.bikeman.com/LT3036.html
both come off the handlebar mount to go in your pocket.
handle bar mount itself comes off easily, also.
I have a Cat Eye made LED taillight I replaced the reflector,
on my Brompton with this one.
http://www.bikeman.com/LT4041.html