This is an arc fault breaker. Q-Line® circuit breakers are one-inch wide per pole, compact, thermal magnetic devices designed for residential and commercial applications. the QL breakers are plug-in versions of the Q-Line® used for connection to loadcenters and lighting panels. all Q-Line® circuit breakers feature quick-make quick-break mechanisms, common trip bars and easy to spot trip indication to ensure safety and reliability. Q-Line® breakers are available in 1, 2 and 3-pole versions, can be ordered with auxiliary contact and shunt trip accessories and can be ordered for use in HID applications.