I believe this is an old New York Police badge based on the coat of arms. It is brass. The engraving says "Police". It has a long pin and clasp in back. It is 2 1/2 inches tall. Good luck!
Some nice ebayer told me that the coat of arms is New Jersey NOT New York. Also, it weighs .8 ounces. Bid with confidence...I will refund your money if you are not satisfied.