Xlab's X-Nut is a tiny, hexagonal, CO2 cartridge holder that mounts behind the saddle; it can hold up to two cartridges and one inflator at once. The X-Nut makes cartridges much more accessible and frees up space in the saddle bag for other items. Mounting hardware included.
The X-Nut fits Xlab's Super Wing and Carbon Wing rear carriers.
CO2 cartridges and inflator sold separately.