This consists of 4 screw-on filters (actually lenses) to fit, in this case, a 55mm lens thread. These are 1X, 2X, 4X and 10X.
I took several pictures of the same subject using same settings with each of the filters:
1X is only marginally different to no filter at all, while 2X is only very slightly greater than this. The 4X becomes noticeably magnified, while 10X is enough to usefully photograph, say, larger insects.
The filters can be combined to some extent, but both 4X and especially 10X have glass so thick and convexed that it protrudes past the depth of the threaded rim. This means you cannot combine 4X with 10X, but any other combination is possible (though less useful).
All four filters fit neatly into the carry pouch provided, although I have decided to leave out the 1X, making a bit more room to easily take out and replace the remaining three.
The filters do not provide quite the same level of magnification as my extension tube set, but now I can combine both. Also, the filters are probably easier to use in the field.
All in all, I would recommend this product. The quality seems very good and, at this price, they're a steal.