RACO Handy Electrical Box Extender - the perfect choice for your ceiling or wall lighting fixture installations! This electrical box extender provides 13.0 additional cubic inch capacity to an existing electrical box. Measuring 4 inches by 2 inches with a depth of 1-7/8 inches, our handy box extender provides ample space to house your electrical connections. With eight 1/2 inch knockouts, wiring your fixtures has never been easier.