Although many PC components create noise in themselves, this can be made much worse when components are installed into a PC case, and their noise can become amplified by the vibration of the metal onto which the component is mounted.
These soft silicone general-purpose washers seek to reduce or eliminate this vibration effect, which often manifests itself as a deep, annoying rumbling sound. Simply put one washer between the device and the metal panel onto which it is mounted, then put another washer onto the screw so it sits under the screw head, then screw the device into place. The silicone washers will sit on either side of the metal panel, and significantly reduce the amplified vibrational noise from the fan, drive or power supply. Easy!
8 washers are needed to mount one fan/PSU/HDD/ODD.