SharePoint Item Permission Batch is used to modify all items
permissions in a SharePoint list.

With this tool you can add or remove permissions to users/groups or
user/group field columns for all items. The user/group field column
are columns which represent users/groups, including "Created By",
"Modified By" etc. inner columns and other users/groups columns such
as "Manager".

Specifically, this tool can help you
1.Add or remove some permission to all items in a SharePoint list,
2.Inherit permission from parent list permission when custom
permission setting is unnecessary.

More information please refer to http://www.sharepointboost.com/batchpermission.html