Bob Co, can you de-codeEaston's numbering system? I have XX75 2020's, but I do not know what that means. Also, if Easton cals out a delfection on their chart, what does that signify?
Chad hit the first question.
People in general refer to Deflection as Spine. Although that is not totally correct.
Deflection is readby suspending an arrow shaftat two points 26 inches apartand suspending a 2 pound weight in the middle. You can use the raw deflection measurement itself, for example .436 inches. Or you can compute the spine using the formula 26/deflection in inches=spine. For example, 26 divided by .436 equals 59.6. You can express the spine of that shaft as .436 inches or as 59.6 pounds.