[rotorwrench]

If you ever had a hard rubber comb, you will know what I meant by that statement about "almost like plastic".

Now days we have so many different elastomer compounds that it's hard to keep up with them all. When I mention rubber it can mean real natural rubber compound or a nitrile or buna N synthetic type rubber compound so I know about ambiguous. The old NOS stuff would not have had a very long shelf life unless it was made with a synthetic elastomer. Natural rubbers tend to deteriorate relatively fast when open to the elements. Just the ozone elements of the air we breath can cause deterioration of natural and some synthetic rubber compounds. Fluorocarbon and fluorosilicone are the longest lasting elastomers that I'm aware of but I doubt if any parts like the ones in question are made from such compounds.