Unknown Silver Brakteat ?

[aidab]

Hi,

This silver uniface piece weights around 0.2 gr and it's size (diagonal) is between 15-17 mm. I'm not sure but it seems it has a letter S at left side of neck's bust.
I would appreciate any help to identify it.

[Salier]

Hallo Aidab,
Schweiz -Solothurn, nach 1377. vierzipfliger Brakteat genannt Stäbler
Brustbild des heiligen Ursus von vorn , im Feld die Buchstaben S und O.

Gruß
Salier