From a system, bought two system, one sync module is enough. Brand new, never used

The Blink Sync Module 2 is a Wi-Fi-enabled device designed for existing Blink Outdoor (3rd Gen) Home Security Systems. It allows users to enhance their security camera setup with added features such as motion detection, live video streaming, and two-way audio. The module is compatible with Amazon Alexa for seamless smart home integration, making it an essential addition to any home surveillance system for added convenience and peace of mind.