In the automotive parts world, it is common to see an additional fee associated with a part purchase called a "core deposit." This deposit is to ensure that the original, worn out part known as the "core" is sent back to the seller.
Specifically, the "core" refers to the main metal casting that can be reused, reground, or rebuilt into a fully functional part that meets the original factory spec. Because most OEMs no longer manufacture parts for vintage motorcycles, it is necessary to have cores to rebuild. Even if an aftermarket company "re-pops" a part, it is rare for this replacement to match the original's quality.
The way the core exchange program works is that when you send us your existing part, and it is in rebuildable condition, you will be sent a rebuilt replacement and refunded the core deposit. If you simply need a part and don't have an existing "core" to exchange, you will receive a core charge on top of the price of the part. This exchange allows us to have a supply of parts to rebuild, which in turn helps all of us keep our bikes running well into the future.