This is an "addon" for the Fan Duct for Ultimaker by Maurits (http://www.thingiverse.com/thing:17768)
The Fan Duct by Maurits is a really nice upgrade for the Ultimaker, but eventually it will warp up towards the aluminum heater block, because it is so thin.
I then made a spacer to hold the Fan Duct down to prevent this from warping while printing.
It is designed to be slid in between the print head and the print head hot end holder as shown on the Pictures.
I have added a Picture with an example of the warping that happens without the spacer (marked with a red ring)
Drawed in Inventor 2012 Educational version