Finland.

Dark-blue ring with white 2 alpha code (on one leg) and metal ring (on other leg).

note 1 : a total of 289 rings delivered since 2018.

note 2 :

White ring with a black three alpha code, starting letter 'C' or 'F' or 'H' or 'J'.

note 1 :
 

Dark blue flag with a white, three alpha code (on right tibia).
Orange colour ring (on left tibia).
Metal ring (on right tarsus).

note 1 : used letters are : A, C, E, H, L, M, N, P, V, Z.

note 2 :

Yellow ring with a black five alpha-numeric code (on one leg) and metal ring (on other leg).

note 1 : first letter "C" / number / letter / number / number.

note 2 : 

Combination of :
​* 2 c-rings (on left tibia).
* metal ring (on left tarsus).
* 2 c-rings (on right tibia).

note 1 : used colours are : orange, red, yellow, white, dark-green.

note 2 : 

Combination of :
* one c-ring (on left tibia).
​* metal ring (on left tarsus).
​* one c-ring (on right tibia).

note 1 : used colours are : red, white, orange, dark-green, dark-blue, yellow.

Yellow ring with a black two alpha-numeric code (on one leg) and metal ring (on other leg).

note 1 : used codes are letter/number or number/letter.

note 2 : 

White ring with a black two alpha-numeric code (on one leg) and metal ring (on other leg).

note 1 : used codes are letter/number or number/letter.

note 2 : 

Orange ring with a black four alpha-numeric code (starting letter 'C'  followed by number/number/letter) (on left leg) and metal ring (on right leg).

note 1 : in 2002 some fifty Barnacles were c-ringed in Finland.

note 2 :

Dark-green ring with a white three alpha code, starting letter 'C'.

note 1 : project starts during 2017.

note 2 : used letters are : A, B, C, D, F, G, H, J, K, L, M, P, S, T, V, X, Z.

note 3 :