As you can see, a modest but welcome increase in magnification. The downside to these filters is that they are dependent on the thread size of your lens, so if you change lenses you may not be able to use the filter any more if the new lens uses a different thread size, plus you are also introducing new glass into your equipment so the quality of the filter will directly affect the quality of the final image.
If you are willing to spend a little more, extension tubes are probably a better solution. These tubes include no glass and so the image quality is purely dependent on your lens, all they do is move the lens further away from the body and this is what allows you to get close to your subject.
Some tubes are extremely simple and offer no connection between body and lens, effectively turning any lens into a manual focus lens (not necessarily a huge issue as many macro photographer exclusively use manual focus) but others such as mine shown below keep the electronic connection between body and lens which allows you to retain auto-focus.