Trajectory listed in the chart is the manufacturers. Shaft manufacturers have design parameters that they apply in the design process to create different performance characteristics. However, most manufacturers usually will test and make the final determination based on field tests. Understand, the designation is more of a guide than an absolute. We assign the MPF based on a number of specs and measurements we check here at The Golfworks. We do not field test every shaft and every flex. Our MPF uses the tip stiffness, torsional stiffness, overall flex profile, weight, etc. and based on the parameters we set, assigns the MPF. Sometimes they mach up with the manufacturer, and sometimes they don’t. Understand, there is no standard for what determines the trajectory profile of a shaft and I have seen “high” trajectory designated shafts actually play to more a mid for some players, and have seen “low” trajectory shafts play higher for other players.