Omer Airbalete M16 x 1.5 , ID = 11 mm I guess, I did not measure so I do not have exact number , L= (39.6 - 12.4 )= 27.2mm , so thread begins after 12.4 mm of flat part with no thread, there is step in side of muzzle, conclusion you can not change it with some other muzzle
Mares Cyrano Evo HF , similar as Airbalete design, you can not change it with other muzzle, M16 x 1.25 , L= (49.75 - 33) = 16.75 mm , also step design muzzle, not simple as regular Mares Cyrano
Mares "Sten 11" M16 x 1.25, ID = 11 mm, L = 17.4 mm
Mares Jet M18 x 1.25 , ID = 13 mm, L = 18.85 mm, there is M18 but actually it is OD = 17.75, similar to other guns where it is M18
Mares Bazooka M18 x 1.25, ID = 13 mm, L = 20 mm
Cressi SL M16 x 1.25, ID = 13 mm, L = 16.6 mm, L is how deep there is thread in muzzle if we measure from edge where it begins
Seac Asso M18 x 1.5, ID = 13 mm, L = 18 mm
Seac Caccia M 16 x 1.5 , ID = I guess it is 11 mm, I do not have gun, L = 18 mm
Mares Mirage M18 x 1.25, ID = 13 mm, L = 22 mm
Mares Mirage, Mares "Sten 13" and Mares Jet have muzzles that can be changed between them.