In 1927, the foot-operated dimmer switch or dip switch was introduced and became standard for much of the century. 1933–34 Packards were equipped with tri-beam headlamps, the bulbs having three filaments. From highest to lowest, the beams were called "country passing", "country driving" and "city driving". The 1934 Nash also used a three-beam system, although in this case, the bulbs were conventional two-filament type, and the intermediate beam combined low beam on the driver's side with high beam on the passenger's side, so as to maximise the view of the roadside while minimizing glare toward oncoming traffic. The last vehicles with a foot-operated dimmer switch were the 1991 Ford F-Series and E-Series [Econoline] vans.