Comparing the styli of the ADC 25. A 3 Stylus Pickup System 

1969. ADC supplied 3 different styli with their "25" Pickup System. Each stylus was supposed to be used with a specific type of record.
One was an all-purpose stylus, but best used on new records. Another was to be used on older, worn records. And one was to be used for a very specific record brand: RCA’s Dynagroove record.
In 1963, RCA developed a new recording process and called it "Dynagroove" and ADC claimed it would sound best with their stylus. While some reviewers and testers agreed, RCA said no matter what stylus is used, the sound will be "spectacular".
Now you can make your own conclusion with this video: ADC’s three styli playing a Dynagroove record.