Battery operated Harmonic movement by Rhythm. * Harmonic movement features a choice of Westminster, Ave Maria or Bim-Bam melodies. Ave Maria and Bim-Bam play on full hour only. Westminster offers 4/4 hour chime (every 15 minutes) or full hour only. * Available automatic night-time shut-off from 11 PM to 5:30 AM * Volume control lets you select desired sound level