https://www.marcospecialties.com/pinball-parts/19-2079
Says it's only 3/8" height for Gottlieb games instead of typical 1/2" height, but that may not make a huge difference?
I bought white 1/2" flipper rubber for a game not even 2 years ago but can't find it now. I was surprised to see "Wico" on the rings when they came in, so maybe they were NOS and finally sold out.