Rather than a polyester number-plug-design, the Aramith concept has the numbers precision-engraved in a solid core that runs all the way through the ball. As such, it is impossible for number-cores to fall out over time. Using phenolic resin assures homogeneous characteristics in each ball part. So homogeneous that when finally getting to its breaking point (and one needs minimum a 5 ton-load in case of an Aramith ball), the ball will break up totally at random, and not along the parting line between the stripe and the rest of the ball, as one would expect.
