Arch support should be used in a cycling shoe before any wedging is attempted as it is the primary method of foot correction for cycling (more here). G8s are suitable for low to high arches with their highest insert (34mm) equating with an eSoles Supportive Black.
G8s have four different arch height inserts included. The arch inserts can be moved in / out or forward / backward in relation to the insole itself for a customised feel and fit. The insoles have a rigid heel cup underlay for better rear foot support and are thinner in the forefoot than previously available offerings giving more vertical space in the shoe toe box than many aftermarket insoles designed for cycling.
G8s are available in four trim to fit sizes with cut lines marked on the bottom.
A comparison of available arch supports can be found here.