Specifications: input voltage: 120 V AC, 60 hz, output voltage: 16 V AC at 30 VA, dimensions: 3.9 x 2.6 x 2.4 inch universal powering for a single doorbell chime or up to three doorbell chimes, thermostatic and more devices in one home. Replace the old and under powered doorbell transformers for better performance. Compatible with Ring Pro and ring doorbells, WiFi and other smart thermostats like Nest and ecobee and more. Not compatible with ring chime pro. UL Certified to guarantee safety and quality. Safe and easy install I on. WARNING: This product may expose you to chemicals known to the State of California to cause cancer or reproductive harm 16-Volt, 30VA doorbell transformer for powering multiple door chimes, thermostats and more, compatible with ring video doorbell, ring video doorbell pro, nest hello, nest thermostats, Honeywell thermostats, nest hello and more, please consult the voltage requirements of your doorbell for specific recommendations Replaces outdated, broken or under-powered transformers, delivers 30VA of power for newer, modern smart devices Quick and easy installation UL Certified Pair with Newhouse Hardware's two tone chimes to complete your upgraded doorbell installation, search for models: CHM1, CHM2, MCHBV or CHM3D