QO Load Centers offer premium features by allowing QO breakers, ground arc fault interrupters arc fault interrupters and surge arresters to be installed inside QO Load Centers enable the use of a full complement of accessories. Systems can be single or three phase and have indoor and outdoor versions. Indoor enclosures are designed to rotate 180 degrees to accommodate top or bottom service entrance feed which saves expensive service cable. QO Load Centers feature plated copper bus, providing superior performance and durability. This accessory for QO and Homeline Load Centers is a screw kit for a trim cover, 10 32 screw size and 1/2 in length.