A speaker unit detachably mountable to a hearing aid device body configured to be positioned behind an ear of a wearer is disclosed. Further, hearing aid device system comprising the speaker unit is disclosed. The speaker unit comprises a contacting unit comprising at least one contact element and configured to be detachably mountable to a hearing aid device connector of said hearing aid device. The speaker unit further comprises a speaker unit body configured to be positioned at least partly in an ear canal of the wearer and comprising an output transducer unit configured to provide an acoustic signal based on an electrical signal input to said output transducer unit via said at least one contact element. The speaker unit further comprises a connecting unit provided between said speaker unit body and said contacting unit and including at least one wire configured to electrically connect said speaker unit body and said contacting unit. Further, the speaker unit comprises a memory unit configured to store data relating to said speaker unit.