tumblebug
My name is NEO!
It is sort of like the multi-layer balls that have since been banned. I do think ASA has figured out how to test these bats to make sure they do not exceed the 98MPH BBS though. Not just compression testing but the actual certification testing.
The main feature in all of the non linear bats is some sort of internal limiting device. Like the discs in the Zs and Combats. I believe the Demarini, Monstas, and others use a foam insert inside inner barrel.
The BBS test is defeatable, I'm just say'n.