The magnents on the the 'no slippy' clip are glued on really well. I forgot to post earlier that another thing I think the magnent does is even out the clip. If you look at a 2 prong or 1 prong clip from the side, you'll see that the tip closes perfectly, but towards the base, near the part you 'pinch' there is space. By adding the thicker magnent, it makes the clip completely close evenly. Resulting in a better grip on the hair. Usually if a clip comes out of the hair, its because its not grabbing the hair evenly, but only partly, so its easier for the hair to slide out.
Again, there's so scientific proof of this, but something I've just observed on my own. So maybe its true, but maybe not.
(again, just lining with velvet will 'even it out'.)