The CARF-Models BOLT! has a special stainless steel thrust tube, which is pulled with 3 springs against the carbon bypass. It has the typical spiral reinforcement for ducted high performance and an aluminum outer tube for coolest running. Since the BOLT! is fully ducted, the thrust tube is a very important part of the inner aerodynamic of the plane and should not be altered, nor purchased from alternate sources or 3rd party manufacturers. 

Please note: The photo above is exemplary and does not show the final configuration.