User-Agent filtering lets you set up inclusion or exclusion rules for browsers or devices based on the user agent string. The user-agent string is used to identify the browser being used by the client and provides information about the browser type, version, and operating system.
User-Agent filtering allows you to ensure that only the browsers you wish to have SSO access to your Atlassian applications will be offered single sign-on. For all other browsers single sign-on will not be attempted. See here for why you might want to use User-Agent Filtering.
EasySSO User-Agent Filtering config screen includes a quick parse-on-demand function to rapidly convert known user-agent string into a format used by the filtering rules.
If you wish to use this feature see here on how to configure it.