Many of the lighting devices on motor vehicles are required and are essential to operation on the highway. To maintain lighting performance, it is important that the bulb and sealed unit types employed be readily available, when needed, throughout the country in normal service channels. Therefore, this SAE Standard lists an assortment of current popular types, together with their design characteristics, which are recommended for use wherever practicable. It is recognized that because of constantly changing and improving technology, the list may be incomplete. Also, instances may arise in the design of some devices which require the employment of other types while achieving the desired performance. Some of the design characteristics in this standard are listed solely for the sake of standardization and have no bearing on how lamp bulbs perform in lighting devices on the highway. A condensed list of specifications and their applicable tolerances is presented in SAE J1049.