No, they did not specify material but on their website Erling listed as OEM Supplier and to add to that, they say:
OEM parts are produced by a manufacturer that meets the high quality standards and produces at least one part for a vehicle manufacturer. FCP recommends OEM replacement as one of the best options for quality and price. Typically all OEM manufacturers adhere to stringent quality control and are known to be exceptional quality. FCP has completed decades of research and we are very stringent with the term “OEM”, rest assured that every product that we list as OEM will be of equal quality to that of OE or Genuine parts we sell.
Both FCP EURO and Pelican parts have 5 star reviews to this gasket

To do the job you only need the 15 grommets from BMW ($20) and the VCG set. The oil filler neck gasket is optional as are the washers, they are not crush washers

The OFHG is a $5 gasket from BMW, stick to OE on that as well. My .02

HERE IS WHAT INSIDE OF THAT ELRING KIT:
This Kit Includes
Qty Part SKU Brand Price
1 Engine Valve Cover Gasket Set ELR-382750 $26.99
11 Engine Valve Cover Gasket BMW-11127838077 $4.29
15 Engine Valve Cover Seal Washer ELR-436010 $0.79
1 Engine Oil Filler Cap Gasket BMW-11127526447 $9.99

OK will get OEM OFH GASKET, Thank you Ricky

I would just stick with dealer sourced gaskets, you have no idea how old the stock is from a 3rd party supplier. I would bet the dealers go through I6 valve cover gaskets like toilet paper.

The $45 for metal flat washers are not needed IMHO. Save the $45, if you really have a problem with the washers, us a hammer and flatten them out, but I do not think I have ever seen a problem with the washers because they just pre-tension the rubber grommets.

I replaced the valve cover gasket on my 330ci with the I6 engine a year ago with dealer parts and it is 100% dry at this point. I have heard of people redoing the valve cover gaskets in 3-6 months with VR or other brand of non dealer gaskets.

Guys, sorry for a brainstorm but how can I determine that airflow meter is dirty? Or just shut up and clean it while it is in my hands? I am really tempted to dig everything out all the way to head from intake side and assemble with new gaskets and good cleaning.... Just to see if I can, i mean doing OFH gasket and PCV, everything else isn't that far away. What can I use to clean inside of intake manifold (it is plastic so I'd out it will be happy to receive brake cleaner shower or not?)?

I would not bother pulling the intake, it is not required and RARELY have see seen intake gasket leaks on these engine.

The inside of the intake is always oily and full of carbon sand. I do not worry about this at all.

As for the MAF, you can clean it, but RARELY do I bother cleaning MAF's, if there is no oil residue in the intake path near the MAF, not sure I would bother.

Come on just use the genuine BMW gasket with permatex and it will not leak. Its all in the technique that one applies.

You've made the best decision by going genuine BMW. When I bought my 540it wagon from the previous owner it needed the timing chain guides. The previous owner accumulated a number of parts for the vehicle such as the valve cover gaskets, timing cover gaskets, intake manifold to engine gasket, etc. Long story short the previous owner mentioned that I am throwing in all these parts for the job that will cut down on the expense that the next owner will incur to repair the vehicle. I had to tell the previous owner that none of those parts have any value to me because they were brands such as victor Reinz, Erling, and Uro which in my book are cheap and last no time. He looked at me and was like they are new. I said you can keep them and fleabay to someone else, perhaps someone who wants to just flip a car. I plan on restoring this 540it to its former glory and only the best will do to make that happen.

If you have the MAF out clean it, but unless you are using an overoiled or excessively dirty air filter it should be clean. Only hose that leaks is the lower intake elbow if it cracks in the folds on the smaller Y-joint that leads to the ICV. A $19 part. I replaced mine when I did my CCV, the original was still fine but it was getting brittle