Black ring with white four alpha code (on one leg) and metal ring (on other leg).
note 1 : example : a/N[IAAZ]
note 2 : rings used at the beginning the letter "I" has two large stipples at the end, so it's often reported as "T"; later the font was changed; however all 4 letters codes always begin with the letter "I" the letter "T" has never been used in the first position of the code.
note 3 : Mauro Fasola ringed in 1991-1998, since then Stefano Volponi is carrying on the field work.