Spoiler Alert: My ratings mean nothing. I haven't bought this filter yet. However, I see the question in my headline both in the Questions about the product and in several users below who ding the product because it uses two polarizers or the filter doesn't work with a CPL. The answer to the question above is misleading and those reviews below aren't fair. Above, the seller says you could add a CPL filter to this VND filter, (true) but, based on what I've read, the results of doing will be very unreliable. Here's why: all VND filters work using two polarizing elements. (Don't complain when your VND has two elements.) One element is a linear polarizer and one is circular. As you turn one, the filter darkens or lightens. Now imagine stacking a CPL filter on top of a VND filter. This really creates three polarizing filters - a linear polarizer, a circular polarizer, and another circular polarizer. That's a lot of polarization for a photographer to keep track of, especially if your VND filter is dialed down so you can't clearly see the shot, which happens with ND filters. Let's pretend you wanted to shoot waterfalls with a VND filter and a CPL filter stacked on top of it. Imagine creating this shot given what I've told you. I couldn't do it reliably. (I might get lucky.) So, if I wanted to shot an image that required both a ND filter and a CPL filter, I'd probably get much better results with both a standard ND filter, which removes the polarization, and a CPL. I hope this helps potential buyers of this item. I'm asking for this filter as a birthday gift. So I'm not a buyer yet, but I hope my wife will be.