This is a mount for Gijs fanduct and other UM ducts.
Fanducts can heat up and sag into print jobs this helps avoid this by disassociating the parts.
This fan mount will allow you to mount your fan away from the hot Ultimaker alloy plate and avoid sagging fans colliding with prints.
#NOTE : Shorten the two inside screws in the Ply Bloks holding the Dia 6mm linear rods. Look at photo attached
Print and mount to your UM. Screw together Fan Holder and Fan Duct with plastic self tapping screws. Fasten with a Polyamide Zip Tie.