Need Help to ID the material under server main board

Hello, we are building some custom server chassis from scratch for a special rack solution. Under and above the main board on my reference chassis there is a black sheet of plastic material. Does anyone know the function of this material and what I should look for to order? One picture is the top panel of the reference chassis, the other you can see the material protruding from under the board. Any assistance is appreciated!

It seems a reasonable guess that this might be some sort of EMI absorption material assuming that it’s just kinda sitting there loosely, underneath standoffs that hold the bottom side of a board well clear of any risk of accidental contact.

If that’s the case, it’s tough to tell from first principles exactly what material properties are required, since it’s the sort of thing one usually only uses because the Oracle at Test Lab hath spoken that it must be so, lest the Wrath of Ephseesee descend upon thee…

Best bet would be to find a material description of some kind from an original bill of materials, some sort of identifying marking, etc. Else one might measure thickness, check if it’s magnetic or not, exhibits any particular electrical conductivity or not, and other such things to try and narrow down how the stuff behaves.

good points, I just took another look at it, It is flexible, stuck to the metal with adhesive, not conductive, not magnetic and is 0.2mm thick.

Nothing in the technical product specs except a picture with the description of “motherboard insulator”