Actualy, I believe is it acoustic foam...

I am at work but I remember looking in the ports with a flashlight and it is foam.

Camera flashes can play tricks on your eyes...most throw blue and so the "appearance" of a see through M60 in Daphiod's image.

WhatFurrer

"Meddle not in the affairs of Dragons, for you are crunchy and good with ketchup..."