Phocas Follis, overstruck on Mauricius Tiberius

Phocas (602-610 AD). AE Follis (36-40 mm, 11.88 g), Constantinopolis.
Obv. d m FOCA PERP AVG, crowned bust facing, holding mappa and cross.
Rev. Large XXXX; ANNO above, CON below.
Sear 640; DOC II, 27.

Struck on on a huge flan. Flan crack, otherwise, very fine.

Overstruck on an earlier Follis of Mauricius Tiberius, with parts of the legends still readable.