Based on this thread, we bought a set of 11 for the regular portlights in our 370. They are pretty good for what they purport to be: an easy way to get privacy in the marina or in a crowded anchorage. They also provide good solar protection. They are very simple to attach and use, appear to be substantial, are overpriced in the way that all the stuff we buy for our boats is, and fit our portlights perfectly. When "open" there are vertical stripes in the portlights, which I don't find particularly attractive (look at the pics on the website and you'll see what I mean), but I don't want the hassle of dealing with curtains. The good news is, that the Clozures are attached via Velcro "buttons" that you press onto the glass. So the entire closure can be removed easily when cruising. The company states they will provide replacement buttons free of charge.
I just left the boat, and won't be back for a bit. Will try to post pics when I get back. They are about $33 per unit.