Not heard of that brand, but not really surprising, there are loads of different names out there for basically the same thing.
They can be useful around water and also have a polarising effect, they are in fact made from 2 polarising filters.
Take some time to experiment, see what it can do for you, they can be very effective.
The one thing not to do is put it on, turn to it's darkest setting and expect it to produce great results. Most are only useable upto about 2/3rds of the way up the scale before they start to get darker in the corners and going further you eventually get a dark X across the image. Find it's limitations and work within them and you should find it a useful piece of kit.