The development of locks with keys during the 13th and 15th centuries of the medieval period was a result of the need for greater security. This constant battle between medieval thieves and making secure locks and keys, in some cases resulted in up to ten locks being fitted on a door. In the later medieval period the key hole was also concealed beneath an ornamental escutcheon plate that was spring-loaded into position. The most popular Locks with Keys in the 13th and 14th centuries was the Medieval Casket Key, which was made from bronze or brass.