This is a replacement Noctua hotend (heatsink) fan.

Note: This is ONLY a direct fit replacement for the MK3, MK3S and MK3S+. See "Fits" section below if you need this fan for an MK2.5/S

Includes:
Noctua Hotend fan (1 pcs)
Mounting screws (4 pcs)

Specifications:
Dimensions: 40×40×10 mm
Speed: 4500 RPM
Airflow: 8,2 mm m³/h (4.83 CFM)
Acoustical noise: 17,9 dB(A)
Max input power: 0,25 W
Max input current: 0,05 A
Voltage: 5V

Fits:
MK2.5 (* requires v-cable adapter )
MK2.5S (* requires v-cable adapter )
MK3
MK3S
MK3S+

To replace this part, please consult the Prusa Assembly Manuals . Make sure to follow the manual for your printer model.