Installation of the Flextion and Flextion HT extruders on the Makerbot Replicator is possible but the existing ducted fan (for cooling extruded filament to improve bridging) mount no longer fits. This is a replacement which will allow the exist fan and duct to be mounted. As this is not in direct contact with anything hot, it should be OK to print it in PLA. In fact, since the Flextion does not use the same extended cold block as the Makerbot there are no holes on it to attach the duct fan mount, so this is screwed into the back of the motor (using replacement, longer bolts for the motor) and the holes on the other fan.