It looks like it was a custom made prop, and Hank's earpiece is different to the one Hope and Scott use.
Hank's is the earlier version he likely has been using for the last 30 odd years with the rounded part that sits near the opening of the outer ear which looks similar in colour to most modern hearing aids, the flesh colour.
The earpiece Hope and Scott use is newer more of a silver pewter colour with what appears to be a clear over the top of the ear part ending with a flattened edge in contrast to Hank's very round end piece.