Most of our remanufactured adsorbers are in stock and ready to ship with or without exchange. If you choose to purchase the adsorber at the exchange price, you are agreeing to ship to us, at your cost, the old adsorber (Core). The core should be the same model number as the item purchased and should not have any obvious physical damage. (Big dents, broken welds) Please ship the core upon receipt of the new part from us. If not received within thirty days from the delivery of the new part, or not useable for exchange, you will be charged the difference for the non exchange price.