This penstock can be used with a computer fan to guide the air away from the bottom of the UMO+ and cool the electronics. The square opening should directed towards the back of the printer and placed next to the back left foot. ! Be careful, you'll need to raise the UMO+ by approximately 4 centimeters. ! ~ Designed for a special case. ~I cut the design into 2 parts to avoid having supports I can't remove in the tube. There are still some left, but I find them easier to remove.