The Tobii DCHU Device Extension is a driver component related to Tobii Eye Tracking devices, which are used for eye tracking and gaze-based interaction with computers, games, and other digital devices. Tobii is a company specializing in eye-tracking technology, and their devices are often used for gaming, research, accessibility, and other professional applications.

The DCHU (Driver Component Host Unit) is a part of the driver suite that allows Tobii devices to communicate effectively with the operating system (Windows) and software applications, providing functionality for gaze tracking and related features. This extension is a part of the Tobii software package and typically installed when you install the full Tobii Eye Tracking driver and software suite.