... the 3 inch air shaft, when work, the shaft can use as 6inch performance. Air Drum A. Air cover has ... B. Usage: set outside the 3 inches air shaft, can achieve the six inches efficientC. Inner bore Ø 76mm, ... alloy hard oxidize, the surface color is tawny,use convenientE. After gassing is equal to 6 inches ... air shaft, outside diameter can reach 155-158mmF. The surface of key bar ...