I would caution against using these and I wish I never installed mine. Besides the "flakes" which may or may not scratch up the playfield, the magnet protector by the prison door was causing the ball to hop and often times go higher than the prison door optos, causing them not to register. I would say this happened about 30% of the time.
I ended up pulling them off using the hair dryer method and thankfully no paint came off. It did seem to leave a stitching pattern indentation around the area where the Well Walker magnet is, but that's only seen in a certain light (sort of like playfield dimples). I'm not excited about that, and I'm out $30, but now my prison is registering hits 100% of the time again and I don't have to worry about obsessively cleaning because of flaking.
I love Cliffy's protectors and use them on all my games. But in this case, I don't think the magnet is needed, based on Stern's new magnet design and evidence out there that this area really doesn't wear. If someone insists on getting them, my recommendation would be to NOT put them on until there is some damage in that area. After all, this protector covers the area that's damaged, so why not wait until there's actual damage there in the first place? An even better method would be to make some protectors yourself made out of vinyl. I've used vinyl magnet protectors in other games and they work perfect. They are thin and the adhesive is strong enough to last, but not strong enough to damage the playfield should you decide to remove it.
Hope this helps.