Brushless Fan DC 5V
It is not compatible with the MaticBox fan adapter. But it can be placed directly on the case body as well. It van fit in MaticBox with the low profile cover. (as seen on the photos)
The price is per one fan.
Here you can find more information about MaticBox innovative case: MaticBox 4
Here you can read our article about fan efficiency and comparison: Which is the most efficient fan for Raspberry Pi 4?
Hydraulic bearing is improved on the basis of oil bearing. Hydraulic bearings have larger oil storage space than oil bearing, and have a unique loop oil supply circuit.