This is a cooling fan shroud for the nozzle fins on a Lulzbot Taz 3D Printer. It helps tremendously for long PLA prints to prevent "heat creep" from causing extruder jams and leaks. It attaches to the left side of the extruder opposite of the official print blower fan accessory. This allows the nozzle cooling fan to run continuously while the print fan is controlled by the gcode and adjusts to your print. This model is still in Beta and being tweaked. Stay tuned for the final version.This fan mounts to the left side of the extruder with M3x12 bolts. Any 40mm fan will work. The easiest way to obtain a fan and wire harness is to buy the Lulzbot fan blower accessory and use the fan, bolts, and wire from the kit. You can find it in the link below. Make sure you get a fan that matches the voltage of your power supply. https://www.lulzbot.com/products/taz-extruder-fan-add-on-kit