Double films consisting of two Ni-Fe layers separated by a nonmagnetic SiO layer show many properties which differ from those known from single films. In the first part of this paper, the energy and the width of walls in double films are calculated. In the second part, the theory is compared with experimental Bitter observations of the walls. Further, domain structures and the reduction of the wall motion coercive force are discussed. © 1966 The American Institute of Physics.