Some golf shafts bend more than others, of course. The letter code represented by the letters L, A, R, S and X represents those different grades of flex.

"L" is the most flexible shaft and "X" is the stiffest shaft. "L" denotes "ladies flex"; "A" denotes "senior flex"; "R" denotes "regular flex"; "S" denotes "stiff flex"; and "X" denotes "extra stiff flex."

Why is senior flex represented by an "A"? When manufacturers first started using this code to denote the flex of their shafts, "A" stood for "amateur," but that level of flex later became associated with senior men.