Why do some Yonex racquets have very long grommets on the throat RDS001 MID RDS001 MP RDS002 RDS003 etc... and some Yonex have short grommets at the throat RDS002 Tour RQis1 Tour RQS11 RQ7 etc... The difference b/w RDS002 and RDS002Tour and RDS001MP and RDS002Tour are the weirdest to me... The 002s are similar construction (if different weights and beam thicknesses) and the 001mp vs 002Tour are very close in specs but grommets very different. What is the purpose of the long grommets and what is the reasoning when it comes to putting short or long ones in their frame designs???? Thx!