Used to mute two octaves at once by pushing between the
groups of strings with a screwdriver of flattened hammer
shank. This is the most efficient way of setting a temperament.
No. 209 Measures 50" L x 3/4" W tapering to
1/2" W x 5/32" thick. These are made of wool, although techs sometimes
refer to them as felt strips.
No. 209T is thin version of No. 209 with a thickness of 1/8".