This is a Litens OAD (Overrunning Alternator Decoupler) that fits the DR-44 alternator and has been modified to accept an 8-rib belt. It has a sophisticated one-way clutch to prevent the alternator from jerking at the belt on hard upshifts and a shock absorbing spring to dampen crankshaft rpm instabilities (heavy camshaft lope). The end result is a much smoother tensioner operation and greatly reduced load spikes on the belt drive system.