The little ceremonial buckler is of the type used in the sixteenth and seventeenth centuries.
On the concave side we see an elegant scene in grisaille with gold highlights, depicting a mythological episode with Diana, Endymion, Cupid and nymphs.
On the convex, and thus on the visible side of the shield, there is a battle scene at the walls of a city. This might be The Fall of Carthage, and thus an allusion to the military feats of the Della Rovere family, or to The Conquest of Pesaro, an episode in 1512 involving Francesco Maria Della Rovere.