vertical windings design on 80's thru 2000's CRTs.

[Wizard256]

On current CRTs, the horizontal windings are open winding on the inside and fits along the curve of bell, but the vertical windings made me puzzled is that ferrite ring is split in half horizontally, held together with spring clips, the winding is wound around the ferrite ring at top and bottom. This wouldn't make enough magnetic field for vertical deflection because of complete ferrite "split ring" yet that did work even there is no gaps. How?

Cheers, Wizard