Redirects the air straight up instead of out. The longer model is for the three center sections, the shorter model goes on the ends. There's a slight gap at the very ends because the outer edges aren't perfectly vertical. Though they weren't designed for it, these work passably to direct the air down if you flip them over and insert the tabs into the second slot from the bottom.
Printed at standard .2mm quality on an Ender 3 Pro with no support. Make sure your bed adhesion is good, though, since there's not a ton of contact.
The author marked this model as their own original creation.