The patented Dual Airflow Stabilizer improves driver effeciency through the air by upto 40%. This improved efficiency makes the head incredily stable during the swing, while at the same time improving club head speed.
Flex as follows with swing speed:
A: 70-78mph
Reg: 82-88mph
Firm: 89 -95mph
Stiff: 96 - 102mph
Strong: 103 -109mph
X Stiff: 110 - 116mph
XX Stiff: 117pmh +