I use these strobe lights, I bought them on Aliexpress (China).
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They are very useful because they have many colours and flashing modes you can choose (you know they must have different color from the ones in use on commercial aircrafts).
I fix them with an o-ring (included) directly on to the left and right motor arms.
Available also in the package an adesive velcro strap.
Two lights are setted up in fixed white light, mounted on the landing gear arms, pointing forward, helps to understand the position and direction of the drone during night flights.
As for all led strobes, these also have a visibility limit when used in daylight environment, but in dusk or night flight you can see them at a very long distance.