Bet progression with KO Fab Five

I've been learning the KO counting system from Vancura and Fuchs's book. For a six-deck shoe it has a ten-stage betting progression, with bets increasing incrementally from 2 to 10 units when the RC is -4 to 4+. The authors also introduce the Fab Five customized count strategy, and say that its betting progression is only over six units (RC 15 to 20), but they never say WHAT the betting progression should be. Is it something like 2, 3, 4, 6, 8, 10? Or is it a typo, and the progression should really be from RC 15 to 25? That would be a lot closer to the six-deck progression for the "original" KO system.