This set of 6 - 100% wool felt temperament strips is the most efficient way of setting a temperament. It is used to mute off the outside strings so one string can be tuned at a time. One strip is more than enough to strip the middle two octaves. Otherwise, in most pianos 2 strips would be enough to mute all but one string on each note for the entire piano. The strip is 50" long and tapers from 3/4" wide down to 1/2" wide. This felt is .125" thick and is made of high density felt for efficient muting.