The HQRP 120V to 16.5V AC 40VA Transformer is a reliable replacement power supply compatible with Zmodo, Nest, Eufy, Nutone, and Ring doorbells with hardwired chimes. It delivers stable and consistent 16.5V AC output at 40VA, ensuring dependable operation and proper performance of your doorbell system. Designed as a practical replacement or backup transformer, this unit is compatible with a wide range of smart doorbells and hardwired chime systems, providing a reliable solution when the original power supply is lost, damaged, or needs replacement. Compatible with Zmodo Nest Eufy Nutone Ring Doorbell Hardwired Door Chime Power Supply Adapter.