I think the protectors are good but they do change the gameplay slightly on some games.

WCS for example has the circular protectors that just won't stay level with the playfield. You can re-tighten and adjust them all day but after a 100 games or so they lift back up. I have seen people go as far as put small pieces of carpet tape underneath to force them flat. I'm not going to do that. Because of this protector lifting balls go air born and others that just stop.

WH20 is another. The VUK protector is super thick which causes hangups and jumping. I have seen people try to remedy this by installing mylar transitions, spring steel transitions, even routing out the upper play field to fit the protector.

Noooo its not your product at all its the installer. Typical response. I really like how on your site the free kick protector shows the start of the lifting. Which is exactly what starts to happen then lifts more and more. Almost every WCS I have seen that has your protecters on them has the lifting issue. Maybe you should address the issue before someone else comes along and starts making a product superior to yours.

Here's a complaint: http://pinside.com/pinball/forum/topic/wcs-cliffy-protector
Another: http://pinside.com/pinball/forum/topic/wcs-cliffy-bending-up

Now this is funny.