On July 1 of 1979, Sony first began to sell the TPS-L2, first known as the Soundabout and soon rechristened the Walkman. This original Walkman wasn’t the first portable tape player, but it was the first that didn’t have a record function. Portable cassette recorders had mostly been used by reporters; this one, with its newly designed lightweight headphones, was specifically intended for music. It changed the world.

That first edition of the Walkman weighed about a pound, and it cost about $200, according to The New York Times. It featured two headphone jacks and a button where the the two people listening on headphones could talk to each other, or sing along with each other, on a microphone. This was basically the last time anyone worried about whether listening to music on headphones, while out in the world, would be a social experience. We now have 40 years of experience that prove otherwise.

It’s weird to think that, in the years before the Walkman, there was no way to listen to music privately while out in public. There were ways to bring music with you — on transistor radios, on boom boxes, on car stereos — but they forced you to subject everyone around you to that music, as well. The Walkman freed us up. It allowed us to make music more a part of our lives, to build our own private soundworlds. It was a transformative invention, one of the few that utterly upended the way we listen to music. Soon enough, more and more portable cassette players would hit the market, and the price fortunately dropped. But no matter which company made them, we still used the word “Walkman” to describe them.

Like so many futuristic technologies of years past, the Walkman is now a relic and a bit of a punchline. Children think it’s ridiculous. But it left a stamp on our culture. That first version of the Walkman is the one that Star-Lord uses in the Guardians Of The Galaxy movies, and it’s selling for a whole lot of money online. If you can find it for $200, that’s a deal.