All right then, no tassels for it to work from casual to formal.

I don't know how these sporrans work, but I am able to remove the tassles on my daywear rabbit sporran; they have split rings on the end of the chains. Just a thought...

It does look like there is at least one mask sporran with horse hair tassels at the STM.

All this can only lead to one question.

If a full mask sporran with tassels is unacceptable for anything but black or white tie attire, then is a full mask sporran without tassels acceptable as a formal sporran.?