•Proto Spline Tools are designed to service high tensile strength fasteners used widely on military and commercial aircraft and in heavy machinery applications where vibration is prevalent. They are also used in automotive and industrial areas where high performance torque needs to be achieved. •Spline fasteners help tighten high strength bolts which are used in high torque load applications. •The Spline profile allows a higher torque to be applied before rounding of the fastener corners occurs. The applied loads are moved away from the fastener corners which allow the spline wrench to turn fasteners that are already worn or rounded. •Spline helps reduce foreign object debris (FOD) by having a precise fit between the fastening tool and its fastener. •Meets dimensional and open end performance requirements of ASME B107.100. •Full polish finish provides corrosion resistance and an easy to clean surface. •Meets Military Spec MS33787 for box end spline profile. •Anti-Slip Design (ASD) open end Patented locking grooves help prevent the wrench from slipping off the fastener when turning. The arched surfaces are designed to spread the contact forces over a greater area and loads are kept off the corners of the fastener which helps prevent fastener rounding.