The halogen floodlight comes in two different types - soft glass or heavy glass. The soft glass type look just like the average incandescent light bulb and are labeled "R" or "BR." These lights are for indoor use only.
The heavy glass type is labeled "PAR" which stands for "parabolic aluminized reflector." This floodlight can be used indoors or outdoors as is able to stand up in severe weather, commonly used in boats, decks, parks and other outdoor areas. It is the only halogen light covered with glass thick enough to stand up in inclement weather. It is available in different diameters, from 1.75" to 4.75." It also is available with different beam widths.
J Type Halogen Bulbs
This halogen light bulb is double-ended and is commonly used as security lighting. A common J Type bulb base is a recessed single contact bulb (RSC) and is 3/8 inch. The J type bulb is available in different sizes and voltages. The volts vary from 12 to 277, and the lengths stretch from 78mm to 254mm. When handling this bulbs, never touch to bare sking. This is not because it will damage the skin; instead, the oils from human skin can reduce the life of the bulb.
JC Type Halogen Bulbs
This halogen bulb is a low voltage bulb, commonly found under counters, in desk lamps or as accent lighting. This bulb can be be purchased in various low voltage amounts, ranging from 6 to 28 volts. This bulbs come in capsule shape and have 2 pins at the base of them. There are two different sizes, a G4 which is 4mm between the pins on the base, and a GY6.35, measuring 6.35mm between the pins on the base. Just like the J type bulbs, a JC halogen shouldn't come in contact with bare skin since it can damge the bulb.
JCD Type Halogen Bulbs
These bulbs are commonly used in under-counter lighting, desk lamps, accent lighting or pendant lighting. They are similar to the JC type in that they have pins on the end, but they differ by using line voltage, from 120 to 130 volts. They come in 3 different sizes, a G6.35 (6.35 mm between the pins), a G8 (8mm between the pins) and a G9 (9mm between the pins). The G9 uses 2 loops on the base instead of pins. JCD type halogen bulbs come in other frosted or clear glass. They should also be handled with gloves.
JDD Type Halogen Bulbs
These bulbs are are used mainly in food service and come in the standard base size. They have halogen filament that is enclosed in glass, then surrounded again by an overall glass jacket.
JDR Type Halogen Bulbs
These small reflector floods are commonly used in range hoods or as track lighting. They come in clear or frosted glass and with, or without, a glass cover. They are either screw-in or with a GU10 base.