Madonna and Child with Saint John the Baptist.
Bronze relief, Italy, mid-17th century period.
Diameter 14.6 cm at the widest.
A similar plaque is kept at the Bode Musuem in Berlin (inv. 1377). Bibliography : Wilhelm von Bode, Königliche Museen zu Berlin, Die Italienischen Bronzen, Berlin 1904, cat1267 (see picture).
Another is kept at the Detroit Institute of Arts, see the last two photos and this link:
https://dia.org/collection/madonna-and-child-and-st-john-courtyard/60274
The casting technique is very similar between the two plaques, see in particular the back and the cold chiselling (which has some variations).
Bibliography: Darr, A.P., P. Barnet, A. Bostrom, C. Avery, et. al. Catalogue of Italian Sculpture in the Detroit Institute of Arts. London, 2002, 2 vols., II, cat. 229.