The Silent Wave Motor (SWM) drives the NIKKOR lens focus mechanism to enable high-speed, ultra-quiet autofocus operation and is a key reason professional photographers like NIKKOR lenses.
NIKKOR lenses with a SWM are identified using the letter 'S' i.e. AF-S NIKKOR 24-70mm f/2.8E ED VR
Silent Wave Motors are widely used in NIKKOR lenses but are particularly beneficial in super telephoto lenses where speed of autofocus, accuracy and silent operation are often key considerations for the user.
A Silent Wave Motor
A compact Silent Wave Motor for smaller lenses