T.A.C 2 1/2 any ideas?

[Robbie]

Ok,here`s one I have no idea,it`s copper or brass and nothing on the back.It reads TAC 2 1/2.Any ideas?

 

[del]

Robbie its very hard to make it out due to the picture sharpness .

 

[leslie(nova scotia)]

hard to see but at first glance it may be a button.