Abstract: A fluid flow control device includes a valve body defining an inlet, an outlet, a throat disposed between the inlet and the outlet, and a bonnet opening, a control element having a valve plug and an elongated stem coupled to the valve plug, an extension bonnet coupled to the bonnet opening, a bellows disposed in the extension bonnet, and a bellows nut threaded onto the stem to secure the bellows in the extension bonnet and form a seal around the stem. The bellows nut includes a first surface, a second surface, a throughbore extending between the first surface and a second surface receiving the stem, and a tapered channel extending from the first surface toward the second surface. The tapered channel comprises a first width formed by the first surface and a second width that is greater than the first width for receiving a tool and facilitating placement.