Top inlet duct for the front 4010 fan on a Vcore4.  

This drops the heat break temperatures by 5C, by eliminating the hot air pulled off the print bed.  Helps in an enclosure where the air is stagnant and prints are often placed in the middle of the bed.  

Helps reduce the chance of heat creep when printing PLA or PETG.   

Print PCCF or ASA-CF for stiffness and temperature resistance.  Print with the 4 holes on the build plate and support the middle of the duct with organic supports.  Paint any surface with 40 degrees of overhang or less.