Some of the first headlights used in cars and trucks after upgrading from candles and lanterns was a housing with built-in filament running on 12v electricity with the name “sealed beam” headlights. It’s called this because unlike today’s modern headlight housings, this entire headlight acted as the bulb. The glass housing was filled with halogen gas and the filament lit up inside just like the filament inside of a modern light bulb.
Sealed beam headlights have been used in new manufacturing even today in some heavy machinery and tractor trailer trucks, however less and less frequently. Today people are still restoring and modifying vehicles from the ’80s and early ’90s that came with sealed beam headlights by installing something called a composite headlight conversion. It’s called a composite headlight because it is produced with multiple components. These headlight components are comprised of a housing separate from the bulb. This allows for easier bulb replacement (instead of replacing the entire housing) and the ability to install HID headlights in sealed beam housings which was not previously possible.
For example, you can install new projector headlights for the Pontiac Fiero (which used 7×6 sealed beam headlights from the factory) which will allow you to have upgraded styling, better light output and HID options or high-power halogen bulbs. All of these things relate to one big idea: Better Automotive Lighting!