question

The hairband is used to wrap around the neck of the guitar, around the first fret.

It's useful for tapping and sweeping, because it mutes the strings you're not playing, but it has it's limitations.

It won't help you develop technique to learn to mute the strings, which is very important. Some people swear by them.

Try it out, see if you like it.

Yea the whole hairband thing is a bit primative, but its usefull for doing the same job when playing slide guitar. Lynyrd skynyrd guitarist used that technique when playing free bird live.