The 4 Pack USB Brushless Cooling Fan is designed for high performance cooling of desktop devices. With a maximum rotational speed of 4200 RPM and a noise level of 22 decibels, these fans are efficient and quiet. Running on 5 volts and using a USB two-pin power connector, they are easy to set up and use. Made of lead material and measuring 1.57"L x 0.39"W x 1.57"H, these fans provide effective air cooling for your computer system.