Watch List notes:

Mexico City, Mexico, cob 4 reales, Philip II, assayer O below denomination oIIII to right, mintmark oM to left. S-M11; KM-36; CT-336. 12.96 grams. XF with light surface corrosion, nice full cross-and-tressure, full but partially flat shield, much legend, unevenly toned.
($250-375)