Add or Remove Www lets you easily configure your WordPress site to always (or never) use the www. subdomain in all links of the posts and pages.
Extended Options keeps meta data and certain WordPress tweaks persistent regardless of the active theme without editing any theme files.
Validates the URL used and if not matching the official permalink then it issues a HTTP 301 or HTTP 404 message.
Lightweight package of several minor improvements for your WordPress. Why to install several plugins? You can have just this one.