A regulating assembly with a valve stem and a valve plug is configured for use in a valve. The configurations may optimize natural frequency to address concerns that operators have with vibrations in devices on their process lines. The valve plug may have a body that narrows from the top and the bottom towards its midline to form an hourglass shape. Reinforcing structure may find use to strengthen or stiffen the body without adding additional mass to the device. This reinforcing structure may include ribs, for example, that circumscribe the center axis. A matrix or lattice structure may prevail as the reinforcing structure as well.