The X-Lab X-nut is an excellent way to hold X-Lab CO2 cartridges and X-Lab Nanoflator or Speed Chuck. It keeps the flat fixing supplies organized and handy. It attaches to Xlab Carbon Wing, Super Wing and Flat Wing systems. The X-nut makes inflating tires a snap during training rides or out on the race course. Holds up to two Xlab CO2 cartridges.