Noctua NF-A4x10 FLX ( 40x40x10mm ) | 40mm | Axial fans | Air cooling | Aquatuning USA
Noctua NF-A4x20 12V FLX or PWM, Premium Quiet Fan (40x20mm, Brown) For MeanWell PSU Upgrade - Smith3D Malaysia
Noctua NF A4x10 FLX 40mm Case fans Quiet Cooling Fan 5V 12V PWM Intelligent Temperature Control Chassis Radiator Cooler Fan|Fans & Cooling| - AliExpress
Creality Noctua NF-A4x10 PWM 40mm x 10mm Ultra Quiet Silent Fan 12V 3-Pin Premium Cooling Fan for CR-10 S4/CR-10 S/CR-10/CR-10 S5/CR-10 mini 3D Printer
These are the most amazing fans for their tiny size (40mm) 5,000RPM at 3,500 RPM silent : r/Noctua