NuTone LA140WH Classic Arched Top Design Decorative Wired Two-Note Door Chime, White Two-note chime for front door and one-note chime for second door Uses 16-Volt transformer model C905 or new C915, sold separately Can easily replace existing two-note chime without rewiring 9-3/4-Inch wide x 6-15/16-Inch high x 3-Inch deep Classic arched top in cabinet-style design