The condition is met if the visitor’s user agent string is match with the condition. You can use Exact, Partial or Regex mode.
Exact mode
If you use the exact mode, the condition is met only if the user agent of the current request is exactly the same as the specified one.
Partial mode
In partial mode the condition is met, if the user agent of the current request contains the specified user agent (part). For example if you set Trident, rules will be applied if the user agent is Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko, or Mozilla/5.0 (Windows NT 10.0; Trident/7.0; rv:11.0) like Gecko
Regex mode
You can use regular expression here. The condition is met if the user agent of the current request matches with the specified regular expression. For example if you specify Windows NT ([\d\.]+) the condition is met if user agent is Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko or Mozilla/5.0 (Windows NT 10.0; Trident/7.0; rv:11.0) like Gecko