Damp!

Many of us would have seen Greg Howe in action with his sister's hair band round his guitar neck. Functionally, it's hair band turned into a string damper. This is the most economical version, of course.

When Jennifer Batten started out (seen here still playing her Ibanez) she had a proper contraption fixed to the headstock of her guitar. This version featured a movable arm to bring the damper down to her strings when required. At other times, it could be lifted away.

The ambidextrous Michael Angelo had one in his guitar as well. The objective of this implement is to mute the strings so unfretted notes do not get in the way. Functionally, it's akin to having a noise eliminating device but it's one mechanically operating on one's guitar neck. Howe, Batten & Angelo are among the many players out there doing two-handed techniques intensively so this device is of great assistance in ensuring open string do not contribute to accidental contacts.

This damper also functions as a ready harmonic generator. Instead of having the fretting fingers do touch harmonics, the damper is a 'hands-free' substitute.