Magnetic Swivel Spark Plug Socket 9/16 x 6 Inch

This socket will not fit over an OEM Motorcraft SP-509 spark plug (plug also listed as HJFS-24-FP on the box). The socket internals bottom-out on the ceramic insulator before the socket flats engage the hex flats on the plug. My truck is an 2009 F-150 with 5.4L V-8 and it requires a 9/16" wrench.