Still uses PK 18 pearl coverstock, with medium low RG (famous Quantum Mushroom) core and low-ish differential.
Depending on drill and your "hand", it's generally for medium-light to medium oil, with strong roll, medium length and arcing backend. If you use a long pin to PAP and/or a highpin position, it will tend more towards a skid/snap reaction, but in general, it is more of an arc-ing type of reaction.
If you got it at a garage sale, you MUST give it some typoe of oil-extraction/rejuvenation procedure and re-surface. Stock finish is 400 grit sanding plus Brunswick's High Gloss polish. If you use a finer sanding, the ball will skid further and hook less.
I have mine at 800 grit plus polish and pin below the ring finger - nice smooth strong reaction for medium-light oil. Semi-control ball because of the lower RG differential which results in less flare, but excellent power/energy retention.
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"None are so blind as those who will not see."