These are very good quality and easy to switch with the existing knobs. They are great if you want to quickly see a specific knob on your mixer.
I wish they did a mixed colour pack ro sold them in 4 rather than 8, as if you want to use 3-4 colours on your mixer, then you end up with a lot of spares and they are relitavly expensive for what they are.
The green and yellow look simular in colour under UV lighting, but you can still tell the difference.
Thomann did take almost a month to deliver these and missed getting them intime for a christmas present . . . not good service.