One of the "best" coverstock( Cytoplacmic Solid) was used on the Or. Cell. I've got "many" games on it( over 600) and still going good. Then they came out with the Mutant; etc. with different "formulae".
Alas, the Mutant did not last at all! pretty dead after 200 games( I take good care of my balls and extract oil frequently). Now I hesitate to get the Theory. What's the chance of getting the Cyto. Solid on the Theory core?
I doubt if anybody can answer that..........but I can dream......