The bracket and duct allow for a 50mm blower (http://www.digikey.com/product-search/en?vendor=0&keywords=603-1370-ND) to be used as a cooling fan. Centrifugal blowers are able to push against higher pressures (small openings in cooling ducts) more efficiently than axial fans and as such allow for better cooling. This is translated into better overhangs on parts (see overhang test image). This is compatible with the e3d v5 hotend and the direct drive conversion here  https://www.youmagine.com/designs/makerfarm-direct-drive-extruder  Installation:1.     Attach blower duct to blower bracket using (3) #3 screws (do not over-tighten)2.     Attach blower to bracket with (2) #8 screws (do not over-tighten) 3.     Align hole on blower bracket with hole on extruder body and insert M3x35mm (or longer) screw. Firmly tighten M3 nut onto screw.