Simply remove the existing plug from the cord, and attach the GFCI plug in its place.  Accepts up to 12/3 SJ-type cords, or 14/3 S-type cords.

 35190 User attachable GFCI plug, 120V/15A, 4 - 6 mA trip level, Auto reset

 14880R User attachable GFCI plug, 120V/15A, 4 - 6 mA trip level, Manual reset

 24230 User attachable ELCI plug, 120V/15A, 10mA trip level, Auto reset