What does "No Friction" mean in Parts "Gear with 8 Teeth Wide, Notched and No Friction" http://www.brickowl.com/catalog/lego-gear-with-8-teeth-wide-notched-and-no-friction-11955

As title, what does "No Friction" mean in the part "Gear with 8 Teeth Wide, Notched and No Friction" ?
In the case of this item, it means that the gear will slide freely along the axle it rotates around.