Studies have shown that using flashing, daylight-visible taillights is the most effective way for cyclists to make it easier for drivers to find themselves. The daytime cycling lights are designed with unique flashing, focusing and light distances that make them more clearly visible during the day.
Can others see you? Research shows that drivers greatly overestimate their visibility.
Features of daytime cycling lights

Not all car lights have the same quality. Brightness is important, but effective daytime cycling lights require much higher brightness. A true DRL, designed with unique focus, blinking and light distance, can maintain a safe distance that attracts the attention of others during the day. Without any of these three elements, all you get is an ordinary lamp.
The purpose of daytime riding lights is to help you “stand out” at critical moments. Using them has proven to be a very effective way for drivers to see you.
In today’s world of absent-minded drivers, taking steps to improve safety is more important than ever. Choose daytime bicycle lights, which are conspicuous up to 2 kilometers away, even during the day, allowing drivers to have more time to see and react.

After I used the taillights, (the driver) was more courteous to me, they would keep a greater distance when they passed me…I told all my acquaintances to turn on the lights when riding a bicycle.
Mads Pederson, Trek-Segafredo
World Road Cycling Championship