Back in the day it was more common to find performance balls that were just core and coverstock. That would be a 2 piece ball. Today Lanemasters/Legends is about the only company that still truely makes a 2 piece ball.
A lot entry level balls and so forth are 3 piece balls. Core, pancake block, and coverstock.
There are 4 components in the Tropical Storm. You have the light bulb core, flip block on the side, the core filler material and then the coverstock.
Most companies will just call a modern multipiece ball a 2 piece ball because it's more of a performance piece.
Entry level stuff usually gets called a 3-piece even if it's not a classic pancake core.
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