The X-Lab Sonic nut An excellent way to hold your X-Lab CO2 cartridges and X-Lab Nanoflator or Speed Chuck. It keeps the flat fixing supplies organized and handy. It attaches to the rear of the Xlab Sonic Wing system. The Sonic Nut makes inflating tires a snap during training rides or out on the race course. It holds up to two Xlab CO2 cartridges.