Not paper at all. They are a engineered fiber
material that has proven itself for decades.
They are fiber end discs
Thats the PC way to call it.. So when you hear fiber end disc... Its cardboard... read below form Wikipedia
Some say cardboard end disc because cardboard is a fiber based paper also.
From Wikipedia, the free encyclopedia
For other uses, see Cardboard (disambiguation).
Cardboard is a generic term for heavy-duty paper-based products having greater thickness and superior durability or other specific mechanical attributes to paper; such as foldability, rigidity and impact resistance. The construction can range from a thick sheet known as paperboard to corrugated fiberboard which is made of multiple corrugated and flat layers.
Despite widespread general use in English and French, the term cardboard is deprecated in commerce and industry as not adequately defining a specific product. Material producers, container manufacturers, packaging engineers, and standards organizations, use more specific terminology