Watch the S.O.S. online guitar lesson by Andy Aledort from 30 Beginner Slide Blues Guitar Licks You MUST Know
This is a four-bar lick played in the key of G, which affords the opportunity to use the open third string as a repeated pedal tone throughout the lick. That "pedal tone" concept provides an anchor to the entire lick, which begins with a fretted note sounded in the same octave as the open third string, but ends on a vibrated G note an octave higher. Because the four-bar lick is repeated over a 12-bar form, it's played three times.