I got asked to rate this product. It seemed churlish not to? So here we go! It is a rubber wedge. It is for use when tuning grand pianos. (Uprights require a quite different device because the cast iron frame is behind the strings and a wedge would not go in far enough. This requires a Papp's wedge or mute.) There are three strings for most notes, two in the upper bass and just one in the bass. Where there are two or more, strings have to be muted, ie silenced a one can work on only one at a time. One needs a pair to tune a grand. There are some plastic ones on ebay for less money. They are not good. Rubber is best as it is pliable. Old fashioned tuners used felt ones: I have found them in old pianos. I just can't touch felt: It makes my hair stand on end. There are other types: Some have a metal handle on with a loop at the end. It is a matter of preference. I prefer short ones,, like these, as my failing eyesight has to be focused right on the gap where the wedge has to go. What more can one say? Very reasonably priced and do the job brilliantly. I keep leaving them in grand pianos all over the place and have to buy them often. Thank you Thomann.