Murray MD breakers take up four 1-Inch spaces and are intended for use in Murray or Crouse Hinds load centers, meter combinations, and multi-family metering where specified. Check the panel wiring diagram to confirm acceptance of this breaker type. This breaker type is intended for applications in which the breaker is mounted horizontally. Murray strongly recommends against the use of “used” breakers. The installation of used breakers in a Murray panel will void the warranty on the panel. Murray does not sell used breakers and has not approved any 3rd party sellers to do so.