2'Fer Front or Rear 2-Pack Light Set
Two really smart, compact USB lights that act as either a front or rear... its a 2Fer. With the push of a button, the 2'Fer can switch between a white 60 lumen front light and a red 20 lumen rear light.
Holding the button for 2 seconds turns the light on and off, and pushing the button once changes modes between white solid, red solid, white flashing and red flashing. The light also remembers which mode you were last using and turns on in that mode.
See How The PUBLIC Community Rolls On Their Bikes.