How things have changed.

When I started my career in communications, these things were made of metal, and made sound by  vibrating flat metal discs, Hi-Fi they weren’t! Some time in the 1960’s, lighter plastic versions appeared.  Now it is possible to pay well over £100 for something which basically does the same thing.
This pair of “cans” was cheap only £60 or so, but they enabled my to listen to loud music without disturbing others, while I lay recovering in bed.