| Project X 5.5 | Project X 6.0 | |
| Flex | Stiff | Extra Stiff |
| Length | 37 – 41 inches | 37 – 41 inches |
| Weight | 115 grams | 120 grams |
| Launch | Low | Low |
| USGA Legal | Yes | Yes |
Flex: Project X 5.5 vs Project X 6.0
The first difference between a 5.5 and a 6.0 is that the 5.5 comes in a stiff flex and the 6.0 comes in extra stiff flex. This means that the 6.0 is slightly stiffer than the 5.5. With the 5.5, its flex is better for those who have slightly above average swing speeds. Whereas the 6.0‘s flex is better for those with very above average swing speeds. Depending on what your swing speed is, one of these will be better for you than the other.
Length: Project X 5.5 vs Project X 6.0
In terms of length, both the 5.5 and 6.0 have the exact same length options. These length options range from 37 inches to 41 inches. This is quite standard in comparison to similar shafts on the market. It should be noted that there is a 46 inch limit on golf shafts. If any golf shaft exceeds this limit, then it is considered illegal. Neither of the 5.5 nor the 6.0 exceed his limit.
Weight: Project X 5.5 vs Project X 6.0
Another difference between these golf shafts is the weight. The 5.5 is slightly lighter than the 6.0. More specifically, the 5.5 weighs 115 grams and the 6.0 weighs 120 grams, which is about a 5 gram difference between the two. While not incredibly substantial, this difference is still something to keep in mind. The heavier the shaft, the harder it is to generate fast swing speeds, but the easier it is to control and vice versa for lighter shafts. Depending on what you are looking to improve, one of these will be better for you than the other.
Launch: Project X 5.5 vs Project X 6.0
Another similarity between these two shafts is the trajectory. Both have a low trajectory which means they are ideal for keeping the ball close to the ground on impact. Through this, you will be able to get a bit more rolling distance on the ball in comparison to other shafts with higher trajectories. If this is something you are looking for, either shaft is a good option.
USGA Legal: Project X 5.5 vs Project X 6.0
In terms of legality, there are many different rules that a golf shaft must adhere to in order to be considered legal. The USGA has a variety of rules that need to be followed. According to the USGA, both the 5.5 and 6.0 are legal to use in any casual, high-level amateur, or professional golf outings.