This is what you need for your doorbells and thermostats, you could be able to charge 2-3 devices the same time, which is a really time-saving tool!
Input voltage: 120V AC, 50/60Hz
Output voltage: 24V AC
Transformer type: UL 5085 Class transformer
This doorbell/thermostat transformer has passed UL certificate,ensuring you have a quality, reliable transformer that will pass inspection