I have two curved 27" monitors and unfortunately, this was a bit too large for it. Since my monitors had raised beveled edges around them, the screen couldn't squeeze in between so I'll just have to save it for future monitors. I did test it on the screen though and it worked quite well. It gave the screen a bit of a darker shade but not anything too drastic, and by stepping aside maybe 15 degrees, I couldn't see what was on the screen at all, except blackness, so I'd say it's pretty effective. See full review