Continental Elite Overrunning Alternator Decoupler Pulleys include a patented internal torsion spring that is tuned to the specific engine application. The spring absorbs base-engine vibration before it reaches the alternator. It also connects, but isolates the alternator pulley from the rotor, which in turn effectively eliminates the vibration felt by the driver. OADs include a one-way clutch (decoupling feature) that enables the alternator to coast freely if belt speed suddenly decreases, such as an engine shut-down or a transmission shift. Lower system tension decreases vehicle noise level, vibration, and harshness, and improves front-end accessory drive component life and fuel economy.