This 100% wool felt temperament strip 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. Material: felt Taper strip width from 0.63 inch to 1.02 inch; Length: 100CM/39.37inch Thickness: 0.197 inch; Color: red Package Contents:1 x Piano Tuning Felt Temperament Strip Tapered Mute Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm. This 100% wool felt temperament strip 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. This 100% wool felt temperament strip 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.