QO Load Centers offer premium features by allowing QO breakers, ground fault interrupters, arc fault interrupters, and surge arresters to be installed inside. QO Load Centers are designed for residential and industrial use to protect electrical systems, equipment, and people. They are available in both traditional and plug on neutral configurations. There is 3 types of mains available. There is main circuit breaker, main lugs, and generator panel. Single and three phase options are available. The bus bars are tin plated copper and are shielded. Indoor and outdoors enclosures are an option. QO Load Centers enable the use of a full complement of accessories. This accessory is a cover filler plate. It is used with 1 phase 150A to 225A convertible load centers.