The Bendix K125791 AD-IS purge reservoir is a genuine Bendix air brake dryer purge tank. A purge reservoir holds a store of compressed air that the air dryer releases back through its desiccant bed during the purge cycle. That reverse flow strips the moisture off the desiccant and vents it out, so the dryer can keep drying the air going to the brake system. Sold by Pro Gear and Transmission. Not sure this is your part? Give us a call and we will help you confirm it.A factory handling fee of $20.00 per unit is added at checkout.FeaturesAD-IS purge reservoirAir brake dryer purge tankHolds the air used to purge the dryer desiccantGenuine Bendix part number K125791