I worked in a setting where we had to use them because people had to get audio prompts but still needed to be able to hear for situational awareness. They definitely work and work pretty well. You can even use them underwater. They can’t match the sound quality of actual headphones though. But for voice stuff or if you’re not super picky about audio quality they’re great, you can easily hear everything going on around you much more clearly than any of the “transparency modes” that modern noise cancelling headphones have because they don’t block your ears at all

They are fantastic for spoken audio like audiobooks and podcasts by themselves, if you’re using them in combination with earplugs they work a lot better for music because you get the low bass sounds that you would miss without the ear plugs.

They’re good for activities you want open ears for, like street cycling. Audio quality is not fantastic though. I use them for podcasts.