# Configure structure and data sync

When you make structure changes to a module, instead of exporting and deploying your site to the target environment, you can use the SiteSync to sync custom fields of built-in modules to the target environment.

To do this, you need to ensure that the structure sync for built-in modules is turned on.

> info  **NOTE**: The following settings apply only to custom fields of built-in modules.

Perform the following:

1. In Sitefinity CMS backend, navigate to *Administration* » *Settings* » *Advanced*.
2. In the left navigation, expand *SiteSync* and click *Structure and data sync*.
3. To turn on syncing of custom fields, select *Always sync structure and data for built-in modules*.
4. Select one or more of the following:
   * If you want to allow users to sync both structure and data, select *Allow Structure and data sync*.\
     This option allows syncing of both the custom field, as well as their values.
   * If you want to allow users to sync only the custom fields without their values, select *Allow Structure sync*.
   * If you want to sync only the values of the custom fields, select *Allow Data sync*.\
     This option allows the users to sync only the values of already synced custom fields, but they are not able choose to sync new custom fields.
5. Save your changes.

> info **NOTE**: These options do not automatically sync structure or data. They only give the user who is performing the site sync to be able to choose these options.\
> For more information, see [Promote content with SiteSync](https://www.progress.com/documentation/sitefinity-cms/promote-content-with-sitesync) » *Select which content to promote*.

> important **IMPORTANT**: You cannot sync custom fields of built-in modules using the single item sync. If your modules have custom fields that you want to sync, use the SiteSync via the *Administration* page.\
> For more information, see [Sync single content items and pages](https://www.progress.com/documentation/sitefinity-cms/sync-content-and-pages).