It never ceases to amaze us about how filthy some PCs can become over time, and it seems that Enermax was so shocked at the number of dirty PC pictures on the Internet (you're welcome) that it decided to solve that problem. To do so, the Taiwanese manufacturer built the new D.F. Pressure fan, where "D.F." stands for "Dust Free."
In order to prevent the fans from collecting dust, Enermax set them to spin in reverse upon startup for 10 seconds at the maximum user-set speed. You can adjust the speed via a slider at one corner of the fan at 1000 RPM, 1500 RPM or 2000 RPM. The minimum speed is always 800 RPM.
If you do manage to get dust to collect, perhaps by never switching your PC off, the fan blades are detachable for easy cleaning, too. Enermax also designed the fan with high static pressure in mind, so the blade structure features nine blades that together push up to 4.812 mm of water. This makes the D.F. Pressure fans ideal for use on water cooling radiators.
The fans have a 4-pin connector for power, draw up to 3.6 w at full speed, and will make between 16 and 27 dBA of noise. Minimum airflow sits at 33.69 CFM, whereas at full speed, the fan can push up to 85.43 CFM.
Enermax did not announce pricing yet, but it did say that the D.F. Pressure fans will be available in May. Each unit will come with three sets of rubber dampers that are plain gray, red, and white to match your system.
Update, 4/28/16, 11:20am: Fixed typo.