I did like the scale used for measuring the return from "radar flag", though
I can't recall
it as an ISO measurement from my days as a student.

Presumably the scale runs

Coot, Duck, Swan, Albatross, Dumbo...

And accounts for the saying

"Less chance than a duck in the fog"

Could you tell us what is a sufficient RADAR target?
I found an old article:
http://www.ussailing.org/safety/Stud...eflector_2.htm
according to which my Mobri "does not perform well".