Pulling this straight out of my ass but I think it’s likely to be polycarbonate

I own a pair. You do lose some functionality without the app. The ability to change the light colors, set and recall presets.

You can still tighten them without the app. And I think you can set one preset as well (not sure tbh)

They announced the sunsetting of the app like 2 months ago but the media is capitalizing on the announcement now for some reason. It sucks but it’s not the end of the world not having the app.