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4 Pack USB Brushless Cooling Fan 40mm Fan High Performance DC 5V Cooling Fan Speed 4200 RPM Fan for Small Appliances Series Replacement Case Fans - Newegg.com
Noctua NF-A4x20 5V PC fan Black (W x H x D) 40 x 40 x 20 mm | Conrad.com
5V 40mm x 40mm x 10mm 4010S DC Brushless 2-pin CPU / Laser / Printer Cooling Fan - Walmart.com
2PCS Gdstime 40mm 24V 12V 5V Fan 4020 Mini Computer Case Cooling Fan DC Brushless Ball bearing Sleeve Bearing 4cm 40x40x20m