Akron Brass FireFox  [3621] 2 1/2'' (65mm) Low Expansion Foam Tubes. The FireFox and Mercury Quick Attack LE Portable Monitor Aeration Tubes now give you the capability to convert your Firefox and Mercury to a foam monitor for Class A or B foam applications, where a heavier foam blanket is desired. Each foam tube comes with a new turbine retaining ring that allows it to easily thread onto the end of the FireFox or Mercury Quick Attack fog nozzle.