Take the AR light bulbs, for instance; they are very unique and used in specific fixtures, like tractors. These bulbs are very unlike the HLX bulbs that are commonly used in portable light fixtures or the PAR lamps typically found in track lighting in retail stores and coffee shops. Yet, this category represents the finest quality light sources available this side of the sun. Halogen light is bright, white, and it shows colors of all types very, very well.
The A-line is a very interesting category, since these bulbs were designed to look just like a regular 60-watt light bulb commonly found just about anywhere. They’re heavier, sturdier, and actually have a bulb inside of them (the glass portion you see and touch is not actually the “bulb”). They are the easiest to use, since they will fit anywhere a regular bulb does. The midbreak was an earlier version of this, with a less-round shape on the glass. Those two types, along with the Decorative ones are pretty much all interchangeable.
For things like music stands and picture frame lighting, the Tubular halogen light bulb is the perfect choice. They’ll fit into the narrow long light fixtures much better than normal shaped bulbs do. They aren’t as long as some standard incandescent tube lights are, but they put out a good amount of high quality light that you’ll enjoy.
Philips made the Halogena brand name very popular, and they did it using the BT15 shape. It’s a unique look, but in the end, it’s pretty much the same thing as a midbreak and A-line. Don’t be afraid to substitute your Halogena bulbs with Capsylite bulbs or other brands, and vice versa. The last thing you want to do is buy from only one brand without regard to the price of the bulb itself. Don’t get me wrong, the manufacturer is important in halogen bulbs, but there are many of them that do a really good job. The top 5-7 brands in light bulbs all have somewhat similar quality standards, so be willing to try another if your brand is particularly high.
PAR lamps are the most popular halogen bulb, and for good reason. Shops and restaurants need the best lighting, and they often need to point the light in a specific direction. PAR lights are perfect for this. The PAR20 and PAR30 are most common, but even the PAR16 is widely used and anything but rare. These are sturdy bulbs that are well constructed and reliable. The average life cycle is typically 2,500 hours for a 120 volt version; double that for a 130 volt PAR lamp. That means the local sandwich shop won’t need to climb up on a ladder and switch bulbs any more often than once every 3-4 months versus only a matter of weeks.
The last major player in the halogen category is the bi-pin MR series. Short for ‘miniature reflector’, they are typically about 2” across and have a two-pin base that can be anywhere from 4-8 millimeters wide. Some of them have a glass cover over them, so the actual halogen bulb inside the reflector can’t be touched, while some do not. The 50MR16 might be the most popular, being installed in projectors, track lighting, desk lamps, and dozens of other places. You might even find that you need an MR light bulb when you replace the bulb in your fiber optic Christmas tree. They turn up in the most surprising places!