If you've been wanting to perform or record in a lower range, and you don't have the time to master the cello, the Sensicore Octave strings let you turn your violin into a baritone violin, sounding a full octave lower than your regular instrument. Octave C string also available, for a true "chin cello".
Sound is decent enough with an acoustic instrument, 'though the body isn't deep or long enough to give full projection to the lower tones. On an acoustic-electric or solid-body electric, however, the sound is amazing. Give your bass-er instincts free rein, and take it down a notch. Have a blast improvising in a totally new soundscape.