This is a Buick Parts & Service Hat Patch. 2" diameter. This is the real deal. I personally removed it from a bad condition mechanic's hat years ago. $23, INCLUDING the shipping.

If you want an original cloth hat topper to use with this patch, please see my current for sale posting for several nice toppers here on Old Gas:
http://www.oldgas.com/forum/ubbthreads.php?ubb=showflat&Number=672271#Post672271