Actually, they're great, but the Stern Cliffy Knock-off is absolutely terrible. It's very thin and as you can see in the pic it broke off on the inside.
It was a PIA to install, plus noticed the guide had chipped off some of the artwork...put mylar down and shouldn't wear anymore as the ball doesn't go over that area. Don't know why Stern doesn't smooth out the bottom edges of these guides.
I'm never selling the game so I won't be losing any money on that little chip LOL.