Helps to install the Profile 48 Spline crank arms onto the Profile GDH 48 Spline crank axle. This tool pulls the arms on the crank axle most of the way. Install and tighten cranks arm bolts to pull the arms on completely. Use the axle anti-seize grease on the splines prior to the install. Make sure you put the right size spacer inside the BB between the bearings. The point is to not crush the bearings when tightening the arms. If the cup sticks out 1 mm from flush with the frame, its no problem.