Perfect fit, easy to replace and will be a great upgrade over your original scratched and or pitted knob. To remove, reach behind the dash and locate the small, round spring loaded button on the top side of your headlight switch. Depress the button while firmly grasping the knob and move back and forth until it releases. To install, firmly and quickly press the knob inward (towards the dash) with the palm of your hand.
Here is a helpful youtube video on how to go about removing a headlight switch from a Cougar or Mustang.