I learned something today that I'm sure all of you are aware of as the days get shorter and the nights get longer.
When riding a bicycle at night a rear red reflector is required. A rear red light does not satisfy the law. "A light-emitting diode flashing taillight visible from a distance of five hundred feet to the rear may also be used in addition to the red reflector."
https://apps.leg.wa.gov/RCW/default.aspx?cite=46.61.780