AFCI and GFCI integrated in circuit breaker. There is no need to install separate devices in series. One place to review all your AFCI and GFCI systems. Arc fault protection throughout the cable, not just from a wall mounted device. Immediate and reliable shutdown with simulated arcing and ground faults in sockets. This device offers a very high level of confidence in the safety of the circuits it protects. I look forward to replacing my main panel with a QO plug-in neutral panel in the near future so I can extend this protection to the whole house, not just the circuitry of the additional sub-panel (although I'm a little less concerned). about the cost, it's cheap insurance). If you haven't worked with Square D's innovative plug-in neutral system before, you owe it to yourself to try it on your next home panel job. No more neutral braids in your panel. Just a nice tidy setup with hot and neutral wires going straight to the GFCI, AFCI and dual circuit breakers and the ground to ground rail. The inside of the panel looks so clean you'll be embarrassed to put the cover on. My only, relatively minor, complaint is that due to the size and relative weight of these switches, gravity tends to pull them down a bit when the cover is off. Panels (not to the point of falling out or anything - just a very, very slight tilt. Once the cover is on everything stays securely in place. Doesn't deserve a one star downgrade, just something to be aware of.