I own a Prince Black and also a Prince White. The RA rating on the White is 65 while the RA rating on the Black is 70. They are both strung with Gut at 58 pounds. When I play with the racquets the stiffness feels very similar. In fact I would say the Black is more comfortable which defies logic and the RA factor. I would think that a RA difference of 5 points would be more noticeable. Can anyone shed some light on this subject?