For a slim to-be-seen light I like the Knog Blinder 4. It is slim, USB rechargeable, has a waterproof design, and is rather solid in the quality department. If you look into reviews you may that some older reviews give it a thumbs down but from my experience I think Knog has improved on some of the flaws seen in the early years for the production of this light. I ride daily and most of the time at night so my Knog Blinder 4 has seen some stuff and some things and it has remained solid for well over a year, all I know is I will be purchasing another one if my current dies/gets stolen/etc(Though I'am tempted by the Knog Arc and Road lights).