The body is a black plastic with the LED built inside. There are two contacts for

the button and two contacts for the LED, one marked + and one -. The forward

voltage of the LED is about 2.2V so connect a 220 to 1000 ohm resistor in series

just as you would with any other LED to your 3V or higher power supply. We'll

note that the LED this comes with is not so great. We really recommend a

diffused LED but these come with a non-diffused one and it wasn't possible to

get them customized. So! We recommend picking up some diffused 5mm LEDs

and winding them into the switch for a better look.

The two switch contacts are not connected normally. When you push the button

they will temporarily connect until the button is released. The LED is separated

from the button, so you can make it light up when pressed, light up when not

pressed, always lit, etc.

 

https://www.adafruit.com/product/4187/5‐29‐19