I got them for use in the shower because I have developed an issue with my ear and it must not get wet. I did not have a positive result, as they do not hold back the water sufficiently. There was no instruction leaflet inside the box of the package. The plastic case in which they are stored has a lid that is difficult to remove because it slips (I would prefer it to screw on and not be a press-on lid).

I didn't buy them for swimming, but for use in the shower, as I am sensitive to ear infections and needed something that wouldn't allow any water to enter.
If they are placed correctly, they are very good, they don't let any water in and they stay in place even with vigorous movements around the ear during washing. After use, you let them dry for a while and then put them back in their case.
The first time I was a little afraid of them and didn't put them all the way in, so of course they weren't as effective. As long as you can hold the edge with your fingers, don't be afraid, they come out easily. Their silicone also seems to be of good quality, I have been using them for a few months now and they are exactly the same as when I bought them.