If your rocker is between sizes for our rocker cushions, adding a Rocker Back Extender as a lumbar pillow under the back cushion or as a headrest pillow above the back cushion is a great solution!
To install a rocker back extender, feed the back cushion ties through the loops on the extender pillow, then tie the back cushion onto the rocking chair.
Here's is a video that shows how to do it: