Padlock of the Polhem type, marked I. Hedlund. The manufacturer J. Hedlund in Eskilstuna made Polhem locks as well as sewing machines. The Polhem lock was popular and was manufactured still after two centuries. The lock was unique for it's time. The key fitted into disks inside the lock. By turning the disks with the fitting key, a notch formed inside the lock and the shackle could open.