This is the software publisher's description.

Unfortunately, most firewalls leak. But Comodo's Firewall is unique in that it passes all known leak tests to ensure the integrity of data entering and exiting your system. Comodo has put our firewall through all kinds of sophisticated tests to ensure our firewall is powerful enough to ward off these attacks with default settings. No other firewall has had to work this hard. Take this test yourself.

Comodo Personal Firewall secures your system against internal attacks such as Trojans, viruses, malicious software and external attacks by hackers.

Safeguard your personal data though a simple user friendly single-click interface offering full immunity to attack. Comodo Personal Firewall helps you connect in a secure way to the internet and global networks.

This is the final and first release of Comodo Personal Firewall 3 and contains support for Windows Vista, a new interface and a whole host of improved security features, including host intrusion protection, network-based firewall and an application analysis engine.

Note that Comodo Firewall is completely free, even for commercial use.