Morris Products 78204 Transformers, 8V10VA, 16V10VA, 24V20VA Voltage Transformer with 120 VAC input and 8 VDC/10 VA, 16 VDC/10 VA, or 24 VDC/20 VA output for doorbells, buzzers, and chimes Thermally protected, Class 2 energy limiting type Screw-hole mounting feature UL listed and CSA certified for quality assurance Fits standard wiring knockout