Square D MasterPacT NT and NW circuit breakers protect electrical systems from damage caused by overcurrent events. In addition to the traditional features of power circuit breaker, Masterpact NT and NW ranges offer built- in communications and metering functions. Masterpact NT and NW incorporate the latest technology to enhance both performance and safety. Easy to install, with user-friendly, intuitive operation and environment-friendly design, Masterpact NT and NW are,quite simply, circuit breakers of their time This auxiliary contact (OF) form C (4a/4b) could be installed on W- and Y-frame drawout MastrPacT circuit breakers.