US Patent 7364536 Weight bar with internally-threaded axial ends

A weight bar for use with a dumbbell having an externally-threaded end is provided that includes a substantially cylindrical elongated bar having a longitudinal axis, first and second axial ends and an intermediate section extending between the axial ends. The first and second axial ends each comprise internally-threaded sections disposed substantially along the longitudinal axis of the weight bar for threadably receiving an externally-threaded end of a dumbbell. The internally-threaded sections of the first and second axial ends each comprise threads having substantially flat thread ends.