You need to download this from Microsoft: http://www.microsoft.com/en-us/download/details.aspx?id=7435.
The tool is called "Microsoft URL Rewrite Module 2.0 for IIS 7" and is described as follows by Microsoft:
"URL Rewrite Module 2.0 provides a rule-based rewriting mechanism for changing requested URL’s before they get processed by web server and for modifying response content before it gets served to HTTP clients"
