If you're selling your used hearing assists online, reveal why you're selling them : Did the first owner die? Did they just not fit your ear comfortably? Did you get a cochlear implant? Potential buyers appreciate knowing the circumstances. If you can afford to, consider giving them instead. When selling or giving used hearing aids, be certain to package them meticulously. Insure the package in case it is lost or damaged en route.
The recipient of a second user hearing aid should take them to an audiologist for correct adjustment. An in-the-ear unit would need a new shell to fit a particular ear. A plastic covered wire that goes over the head customarily attaches them to one another.