Useful to help your quilt slide, but---- I have found that while it sticks well to some machines it doesn't do so well for others, as a result I tape mine at the back and also at the far right side, that way I can lift it up to get to the bobbin area on my PQ without having to completely remove it.
Another problem I have found is that over time the needle opening will become warped which causes it to lift along one side, this will catch on the quilt which is a pain when FMQ. To solve that problem I cut an opening large enough to fit around the needle plate. This also allows me to keep my slider on my machine all the time since the feed dogs will be exposed when raised and the seam lines marked on the needle plate are visible. For me it works just as well as it did with just the small needle hole and I can quickly switch from FMQ to piecing without having to remove, rinse and dry the supreme slider.
I also tried the silicone spray, but worried about gettingit in the oiling holes on the bed of my machine. I also found that I had to reapply it frequently.
Rob