The Pitch-Key is recommended for use on steel strings of gauges down to 0.054". The extent of available pitch drop varies according to string gauge, tuning and scale length of your instrument. The table above shows the scope of a Pitch-Key fitted to a 25.5" scale guitar at standard pitch.

Note that you can set the Pitch-Key to raise or lower the pitch of the lighter strings. Due to the higher forces involved, the Pitch-Key should only be set to lower the pitch of the heavier strings.