Sonnet includes Slider Revolution by ThemePunch. You can use Slider Revolution inside Sonnet for free. Please note that it is not a freeware though. You can not use it apart from Sonnet unless you purchase the appropriate license.
If you have Slider Revolution Plugin, activated on your site, you will have the Slider Revolution Element available through the Sonnet Page Options, the Sonnet Post Options and the Sonnet Product Options.