The shake proof washer is one of the best things to happen to cases in quite some time. One of the biggest causes of fan noise in a system is the transfer of motor vibrations between the case fan and its mounting. This vibration can travel through your case causing your side panels to rattle like steel drums. These washers prevent vibration from transferring into the mounting there by preventing such noise. The washers also are ideal for absorbing shock, which is helpful if you move your system a lot.