A security-protected item comprising:
- a first frame and a second frame or an assembly of a security-protected item including a first frame and another object including a second frame,
- the first frame including a number n of first frame sub-frames each consisting of first frame first elementary patterns separated from one another in at least one common first frame extension direction by first frame second elementary patterns, the first frame first elementary patterns all having a same first frame first pattern dimension x1 in the first frame extension direction and the first frame second elementary patterns all having a same first frame second pattern dimension x2 in the first frame extension direction, the first frame second elementary patterns being of visually different appearance under at least one given illumination condition of the first frame first elementary patterns,
- the n first frame sub-frames being all phase shifted relative to one another in the first frame extension direction by a distance dxij less than x1+x2 and substantially equal to a multiple k of a smallest phase shift m between the n first frame sub-frames, k being between 1 and n−1 inclusive, n being greater than or equal to 3, the smallest phase shift m being different from a multiple of a smallest dimension x1 of the first pattern of the first frame and x2 of the first frame second pattern in the first frame extension direction,
- the second frame consisting of second frame first elementary patterns separated from one another in at least one second frame extension direction by second frame second elementary patterns, the second frame first elementary patterns all having a same second frame first pattern dimension v1 in the second frame extension direction and the second frame second elementary patterns all having a same second frame second pattern dimension v2 in the second frame extension direction, the second frame second elementary patterns being of visually different appearance under said at least one given condition of illumination of the second frame first elementary patterns,
- a distance equal to x1+x2 in the first frame extension direction being a multiple of a distance equal to v1+v2 in the second frame extension direction,
- the item or the assembly being configured so that, when the first frame and the second frame are superimposed the first frame is visible at least in part at least through the second frame second elementary patterns and/or the second frame is visible at least in part at least through the first frame second elementary patterns.