Niagara Cutter brand C2 cutter head for milling machine.  3 1/2" diameter R.H.  1 7/8" thick.  1 1/4" and 1 13/16" center bore.  Does not appear to have ever been used.  Unknown what machines it will fit.  Has 1/2" diameter x 1/4" deep channel across the top side.  Has some very minor surface rust from storage.  Otherwise excellent condition and with the original box.