From the application’s product page:
Roadblock has a comprehensive and optimized built-in block list for blocking and hiding different types of content. You can easily block ads, tracking, social media, and web resources.
Custom Rules provide a powerful yet simple way to create, manage, and share your own rules. You can create custom rules to block resource and website loads, hide webpage elements, strip cookies from web requests, and whitelist websites.
This is a great looking content blocker for the Mac. If I used OS X on a regular basis, this would be an insta-buy.