Flex refers to how much the shaft of the golf club bends during the swing. There are generally five ratings for flex: extra stiff, stiff, regular, senior, and ladies. Your optimal flex will vary based on your technique and driver distance.
| Flex | Driver Distance |
| Extra stiff | Over 275 yards |
| Stiff | 240-275 yards |
| Regular | 200-240 yards |
| Senior | 180-200 yards |
| Ladies | Under 180 yards |