This plackart or reinforcing breast-plate is made to fit over an armor to provide additional protection against firearms. This allowed protection when needed and a lighter more maneuverable armor when it was not in place. A number of such reinforcing breastplates were produced for the Tower of London in the 17th century though surviving examples are rare. See European Armour in the Tower of London, Pl CXXI, c for a similar example and, Pl CXXI, d, for an example as mounted to the armor. Item #1, adjacent, is a pikemans armor made for use with or without the additional protective plate.