Halogen bulbs are incandescent bulbs. Halogen bulbs, however, are filled with a special gas that actually rebuilds the filament and lengthens the average lifespan compared to normal incandescent bulbs. They come in different shapes and sizes for various different uses. The MB19 series of halogen bulbs are shaped and sized similar to the standard A-Line (ie: standard run-of-the-mill light bulbs) bulbs that are used by almost anyone with light fixtures. They have heavy, thick glass that is common to many medium to large sized halogen bulbs. 'MB' stands for midbreak, which refers to the unique shape this bulb has had since its inception. '19' shows the diameter of the bulb, in eighths of an inch; the MB19 is 19 eighths or 2 1/8 inch. Recently, manufacturers like Osram Sylvania have made the shape like a normal light bulb, with rounded contour instead of the blocky MB19 shape. These types of bulbs will provide you with a higher light output, a more white-colored light (a higher color temperature - approximately 3000K), and longer life than normal A-Line light bulbs.
The MB19 halogen bulbs can be found being used in all sorts of locations. Garages, table lamps, outdoor fixtures, basements, and locker rooms are a mere beginning of the list of possibilities. They will easily fit anywhere a standard bulb will.
MB19 halogen lamps are widely available from Sylvania, Westinghouse, GE, and Philips. They have medium (standard) bases and are able to be used indoors or outdoors. They are offered in two varieties: Midbreak and Crystal. Midbreak bulbs will have a smooth feel to them and will provide normal halogen light characteristics and qualities. The Crystal version will cause the light to emanate in a sparking fashion. This effect is quite stylish and really contributes to many different decorative applications.
The Sylvania brand for all MB19 lamps is Capsylite. The Westinghouse line refers to the MB19 as a BT-15 or BT15. The Philips brand for all MB19 lamps is Halogena (Philips refers to this bulb type as BT15 and Halogena Classic instead of MB). The GE brand for all MB19 lamps is Edison (GE refers to this bulb type as a TB19 instead of a MB).
You can get MB19 bulbs in 120 volt only. However, the fact that the bulb is a halogen bulb means the average rated life will be considerably longer than a standard incandescent bulb.
Please consider the additional heat that an MB19 bulb will create when choosing the right model. Halogen incandescent bulbs produce, on average, 10 percent more heat than a standard incandescent bulb of the same wattage. If your lamp has a shade that may be susceptible to the increase in heat, take care not to use too strong of an MB19 bulb in that application. You may want to choose a lower wattage MB instead of a full wattage standard bulb in order to get whiter light, longer life, and more lumens per watt that a halogen bulb can provide.