While revisions can be disabled or limited in number with settings in the wp-config file, there is no way to allow for the deletion of revisions over a certain ago. That is what this plugin allows you to do. In the options you can set the number of months after which revisions are to be deleted. They can then be deleted at the click of a button or via a cron job running on a daily schedule. The options also allow you to select the post types (both standard and custom) which can have revisions removed. Removal of revisions is done using the ClassicPress function to ensure they are done correctly. This plugin is multisite compatible, with options set on a per site basis.