I bought a set of both rubber and felt mutes for piano tuning, as I had no previous experience to inform me. After using both, the rubber mutes are clearly easier to use and better at muting than the felt ones.
I rated 4/5 stars on the "quality" only due to a somewhat rough, "just off the machine" finish that could be improved. Of course, for 1,50€ a mute I am not complaining.