NuTone LA18WH Decorative Wired Two-Note Door Chime with Vertical Panels, White Two-note chime for front door, single-note for second door Uses a16-Volt transformer(C905), sold separately 7-7/8-Inch wide x 8-Inch high x 2-1/2-Inch deep Replaces NuTone LB18WH Vertical panels, white finish