This is a fan duct that can be attached over top of a fan to force air more towards the extruder tip. Potentially giving better PLA prints. I always found that printing certain parts in PLA on the 3d touch can be messy (especially small, high res parts with large over hangs).I did some test prints and they turned out really good using the increased air flow and having it directed near the nozzle tip. Even large flat PLA parts came out really well!EDIT You no long need to move the limit switch. I added a pocket into the model that should clear the limit switch. Print Rev2 for that change.Edit Added Fan duct for front right position (I'm sure it can also be move to the left spot too). Tips on moving the limit switch: http://www.bitsfrombytes.com/usd/forum/post/heated-bed-0?page=10#comment-36957 Also a link to a Thiniverse page with a printable mount and explanation http://www.thingiverse.com/thing:26182 Step 1: Install aftermarket fans. They must be bellow 15mm so as it will fit and not crunch into the build platform. -Here's an example of the fans I got. I tried to maintain the same specs that were on the stock fans(http://www.digikey.ca/product-detail/en/KD1206PHB1.(2).GN/259-1337-ND/1021186)This link is strange only works if you copy and paste the whole thing :P. -The fans I got are powerful, main difference is the higher RPM. Which also increases the noise output.Step 2: Print part... with support (sorry).