Metal shell,100% brand new and high quality,mechanical life for 500,000 cycles
The switch and LED are separated, LED can be on all the time or only on when switch is on,depending on how you wire it
Can be use as a switch for various additional electric equipment, inside & outside the car.(Such as critical lights, chassis lamp, fog lamps, dome light)
There is a wiring instruction in the packaging. You can get the wiring diagram in it, that can help you to install