The chapter provides an overview of the MS4640A Series VNA hardware user interface including front panel buttons, front panel connectors, and back panel connectors. Included are photographs of the front and rear panels. Each front panel key is described with its function and a cross reference to the menu it activates on the user interface display. Each port and connector is described with its connector type, its function, input/output limits, and a cross-reference to a detailed connector pin-out diagram.