Fishman AURA ACOUSTIC IMAGING PEDAL User Manual page 7

Use the Concert pedal with small-
body, short-scale instruments with thin
waists, like 0, 00 and L-00 styles;
typically finger-picking guitars as
well as parlor and travel instruments.
For guitars larger than concert
but smaller than dreadnought, the
Orchestra pedal works well with
OM & 000 styles as well as auditorium
and other narrow-waist mid-size,
medium-depth instruments.