This is a design to change the original extruder to an MK7-MK8 extruder.
This thing should be assemble together with Qu-bd Oneup / Twoup Bearing holder for extruder, and probably with some parts of the original holder.
This thing should be used with http://www.thingiverse.com/download:413359
You should remove the thin external parts that are used like support for the important part.
It has added a fan mount for the original fan that uses this printers.