This post is just a microcosm of how screwy the numbering systems can get.
Just like Big B and their C-system balls. They had the 2.5, then came the 3.5 which was strong, setting the stage for the 4.5.
Because the 4.5 was numerically higher, many though that meant it would be stronger (Read: handle oil better) than the 3.5, but that just wasn't the case, so many who got it with that assumption were displeased.
When you give the public something with BUILT-IN preconception, such as a numbering system, confusion and disappointment are sure to follow.
EXAMPLE: How can a 5 series ball possibly outhook a 9 series ball, especially since the 9 series cost more and is supposed to be a higher performance level ball?
Not too hard if the 5 series ball is the 505T with a matte finish.
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Good transactions list in my profile