What does it do?

This extension returns device detection to your TypoScript conditions, which have been available for quite some time, but were abandoned with upcoming responsive design. Still it might be useful to detect several devices and to provide certain frontend outputs only for a specific device or based on other specific user agent information.

You can use the conditions just like any other TypoScript condition based on Symfony Expression Language. See Configuration for a listing of conditions currently provided by Device.