ARCTICS4028-6K (5 Pack) - 40x40x28 mm Fan, 250-6000 RPM, PWM Regulated, 4-pin Connector, 12 V DC - Black

ARCTIC S4028-6K (5 Pack) - 40x40x28 mm Server Fans, 250–6000 RPM, PWM Regulated, 4-pin Connector, 12 V DC, Rack Cooling Fan - Black

Noctua NF-A4x20 PWM, Premium Quiet Fan, 4-Pin (40x20mm, Brown)

Noctua NF-A4x10 FLX, Premium Quiet Fan, 3-Pin (40x10mm, Brown)