Cross cylinders is
A i.e. One plus cylinder and one minus cylinder of equal strength Cross cylinder is a combination of two cylinders of equal strength but with opposite sign placed with their axis at right angles to each otherQ and mounted in a handle. Jackson's cross cylinder test is used to verify the strength & axis of the cylinder prescribed. The commonly used cross cylinders are of +- 0.25 D and -0.5 D.
One plus cylinder and one minus cylinder of equal strength
One plus cylinder and one minus cylinder of unequal strength
Two plus cylinders
Both minus cylinders