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 single or multiple door chimes, thermostat and more devices in one home. Upgrade your home security with the Newhouse Hardware 30TR Doorbell Transformer. This UL certified transformer is designed to power up to three hardwired doorbell chimes or modern smart doorbells without any issues. With an input voltage of 120 Vac and 60Hz, it ensures high-quality video resolution and eliminates connection issues caused by underpowered transformers. The compact and lightweight design of this transformer makes it easy to install and it comes with a thermal cut-off switch that offers an extra layer of safety by shutting off power in the event of excessive temperature. It is compatible with Ring Video Doorbell Pro, Nest Hello doorbell, Nest thermostats, and other smart doorbells.