Me 109E Armored plate

I am building the Tamiya kit and there is am armored plate that goes behind the pilot. One side is roughed plastic( metal in real life?) and the other side is smooth. What color would that plate be?

The instructions should tell you what the appropriate color is.
What 109 E #? are you building? I’m working on a 109 E3 and the instructions specify the color. (which I don’t have on hand right now)