Watch List notes:

Uncertain (L. Saufeius?). Fourrée brockage denarius, mid 2nd century BC. D/ Helmeted head of Roma right. R/ Incuse of obverse. AR. g. 3.56 mm. 18.00 Unicum. Excessively rare, apparently the only specimen known of both fourrée and brockage denarius. Plating broken in spots. Good VF.

Individually, fourrée denarii and brockage are rather common. But this example exceptionally combines both of these varieties. About fourrée production techniques, see: Campbell, William - Greek and Roman Plated Coins - Numismatic Notes and Monographs No. 57, ANS, 1933.