Our state law requires a red rear reflector on bicycles, even if there is a red blinkie light on the back, so I have both. I use the rear blinkie even during daylight hours if I am riding on the road. Most of the others that I ride with do the same. As we've ridden this summer, I've noticed that especially on wooded roads as we pass from light to shadow, the bikes with the blinkies are much more visible from the back.