Copy of a key from the Swedish National Museum showing tines the working end that match a pattern inside the lock. The key rotates the lock to open it. Each lock and key was unique and duplicates were rare so the locks were quite secure. This is the largest bronze key I have found in the Swedish National Museum collection, larger keys appear to have been made of iron.
90mm L x 30mm W or 3 5/8″L x 1 18/”W Bronze