There are four groups within the Scale Series, Alpha, Beta, Gamma, and Delta, covering from 72 to 84mm underfoot...frontside to narrow AM categories.
What's interesting is their sizing... For each of the four groups, the width underfoot gets wider by 1mm as the length increases by 10mm, while the tip and tail widths stay the same. Each group comes in four lengths in 10 cm increments from XS, S, M, to L.
Alpha (XS=151cm) 73, 73, 74, 75mm
Beta (XS=153cm) 75, 76, 77, 78mm
Gamma (XS=155cm) 78, 79, 80, 81mm
Delta (XS=157cm) 81, 82, 83, 84mm