One thing I've not liked about my pool is that we don't have any lighting for night swimming. I've looked at several options from the floating lights, to ones that hang over the sides, to the permanent installed versions. We'll need to replace the liner in a few years, so really didn't want to get into the permanent version until then, that and the cost of LED, low voltage options are coming down in price. Last year I tried the floating ones, but they were pretty weak and constantly were floating down into the skimmer.
This year I found the style that screws into the return eyelet sockets. They have a small impeller built in that generates power for a ring of LED lights around the outer edge. The base has a 1 1/2" standard thread and the eyelets are adjustable to direct flow. The reviews were mixed on them, but decided to give them a shot. I ordered a two light set for $39.00
They stick out just a little more than the standard eyelet, but not bad.
The pics aren't quite a good representation, they are quite a bit brighter in person, and much better than no lights at all.
Since they are self powered, they only run when the pump/filter is on, which we normally do turn on when swimming. Also, I did a check of the pressure gauge after a good back flush and rinse, then before and after installing the lights, the pressure was the same and flow seems to be the same.
Overall, I'm impressed with them, hoping they last a while and even come out with improvements for future versions to get them even brighter.