The Rubber Anti-Vibration Screws not only mount your case fan - they dampen the vibration between the case (or other mounting surface) and the fan. This results in up to a seven decibel decrease in perceivable noise of a mounted fan. Each package contains four fan vibration isolators which are compatible with standard fan screw holes and fans with open corners. The standard fan screw hole size is 7/32" (5.5 mm). Please double check your fan and case for compatibility before purchasing. These fan mounts work with our 80mm, 92mm , and 120mm case fans. They don't work with 60mm case fans since 60mm fans have a smaller hole than the 7/32" standard fan screw hole.