https://www.theverge.com/2017/9/20/16337562/nest-secure-guard-detect-tag-alarm-home-security-system

Nest is getting serious about home security with an entirely new product family it’s calling Nest Secure. Announced today at a hardware event in San Francisco, Nest detailed a new modular system that is designed to make home security more modern and simple.

The centerpiece of the system is called Nest Guard, and it’s a small, hockey puck-shaped device with a keypad on top. The device sits at your front door and communicates with a smaller device, called Nest Detect, that can be placed throughout your home. If anyone enters the house and doesn’t disarm the Nest Secure system, the alarm triggers and a large loud siren sound is sent out. For every action along the way, the system sends alerts to your phone.