These bulbs are often made of glass, with little exposed metal. They provide a large amount of light and get hot quickly. The LED replacements are often slightly dimmer, but provide a huge energy saving.
The incandescent bulbs are available in 5 watt, 10 watt, and 20 watt variations. The LED replacements for the 5 watt and 10 watt models can often match or exceed the light output of the incandescent bulbs. In many cases, these bulbs are used in older light fixtures, or in instrument panels.