Device
By default your experiment will run for all devices. If you only want to target specific devices you can do this with a Device condition. Simply add the device(s) that you wish to include, and the others will be excluded.
Example
In the example above above the experiment will target desktop and tablet visitors that visits Product Detail Pages (where an element with an ID of addToCart exist).
tip
Always test your Audience in Preview before activating the experiment to make sure that your experiment only runs on pages that you intented.