Mexico City, Mexico, cob 1/2 real, 1615/4F, very rare. S-M17; KM-unl (type 21). 1.57 grams. Broad flan with choice full monogram (a few old scratches) and oM-F, full and clear date with bold overdate (first specimen we have recorded), good full cross-and-tressure, VF with toned fields. (Estimate: $250 - 375)