[SOLVED] cooler mounting safety question about missing pieces

[1337Skrjabin]

Hey guys, so I wanted to install my old macho rev b into my friend's pc but then I found out that my kit is missing 2 pieces.
I'll upload a photo of them. They go in between mobo's backplate and the mounting platform, for safety reasons I assume. So I wanted to ask whether it would be safe to install a cooler without these 2.

 

[Lutfij]

Make and model of the motherboard? As for the two missing pieces, the mylar film and the backplate cap(and washers go) before the metal bracket on the underside of the motherboard to prevent a short. If you don't have the mylar parts, you should avoid using the cooler.

 

[1337Skrjabin]

Make and model of the motherboard? As for the two missing pieces, the mylar film and the backplate cap(and washers go) before the metal bracket on the underside of the motherboard to prevent a short. If you don't have the mylar parts, you should avoid using the cooler.

It's Gigabyte ab350m-ds3h v2
So, the point of mylar is to avoid heat? And what's the purpose of that plastic cap?