It is the SmartFit that you already have. I don’t think it would prompt you for a code. They like to be secretive. Though, I could be wrong.
ETA: In the other thread it turns out the hearing aids were not locked after all. They were just left-as-connected to Bluetooth Streaming and therefore would not connect. Once Bluetooth was turned off and the hearing aids were off/on cycled then they were able to connect to SmaftFit the same as any not-locked hearing aids.