The Specter Bangle does not give the invisibility effect. You can see the particles. I tried it in Creative and Survival (with ME).

I do not understand. Then what is the ability

Invisibility but like not with a potion effect

Press F5 to find out lol

I did it, it was still visible and the mobs saw me too

It's not supposed to give invisibility, it disables the rendering and adds smoke particles