They work well and are cheaper that any metal alloy solution, plus easier to put on and pull off, no tools required. They also won't fit on any switch, though grand majority of pedals I have accept them well - there are some exceptions with smaller than regular switch knob. And yes, they are plastic, so I suppose they can tire up or crack, though I haven't managed to break any during use. Color range is a nice bonus, if you are a visual junkie like me.