This is a ducted of double way correct for fan 50mm. and hotend J-Head MK-V for printers Mendel Prusa version 2. The air is driven efficiently to the piece and directly to the heat sink of hotend J-Head MK-V keeping the nozzle hot. You will need bolts and nuts metric of 4mm. Two versions available, with and without mount plate and original 3D file for SketchUp too. You have that to remember this piece only fit over a X carriage, with three linear bearings LMM8U type like this iearobotics.com/wiki/images/1/1e/DSC05555.JPG
To avoid collision with the four bulldogs paper clips, I recommend using kapton tape around the perimeter of the glass to attach it to the hot bed. The print dimensions are greater now.
Now, there are three new STL files available. You can glue them to get the complete shape named "Double_ducted_for_fan_with_mount_plate.stl"
Use this option to combine three easy printings, where the support material isn't essential and get a functional object, though, for best results, it is still highly recommended to use.
The objects are named: Element_A.stl, Element_B.stl and Element_C.stl