The material is superb, feels like a hybrid of hard candy rubber and thick elastic plastic. They are also partially transparent, except at the core and the edges. If there is a light source underneath, it will light the whole topper up too, which is extremely useful on a dark stage! (Unless you order toppers of a darker colorisation, which will spread, but also dim the light a tiny bit.) Placement is firm, hold's proper, removal easy.
My only complaint about the product is that the color hues pictured on the photos are slightly, but definitely brighter than the real deal. This blue one is not "that" light blue, more like a medium blue, or semi-dark blue. Please also note that the topper WILL NOT SHIFT the color of your pedal lights: red will remain red, it will only be filtered through the toppers' blueish (or whatever color you've ordered) frame. ROSEY toppers (and I must assume that RED ONES especially) however spread AND elevate red lights on their whole surface, probably because of the close alignments of hues.
Still, I definitely recommend buyind these! Just look up (or change) your pedal lights, if you want the rainbow to really shine through. ;)