50x50x10 mm Quiet cooling fan, 12v, 3000±10% RPM, 30,000h MTTF. They are durable and you don't need to buy another small fan in the next 30,000 hours. Use these 23 dB cooling fans to get near-silent operation. Ideal replacement for noisy or broken 12V 5cm fans in 3D printers, DVD players, DVRs, switches, other network and storage devices, etc. The 9-blade fans can be run 2700 to 300 rpm by fine-tuning the fan for maximum airflow(6.25 CFM) You will need a battery pack/power supply that supplies 12vdc and has a capacity sufficient to provide 100ma to make the fans run. A 2.5mm pitch 2-pin connector makes it compatible with your computer motherboard or 3D printer power system. Please kindly contact Icstation Service Team at icstationathotmail if you received a damaged/wrong product. We provide free replacement and tech supports.