I believe that the paper is referred to as "Vapor Corrosion Inhibitor" paper.
Here's one definition "Volatile corrosion inhibitors (VCI) are a type of corrosion inhibitor that are used to protect ferrous materials and non ferrous metals against corrosion or oxidation where it is impractical to apply surface treatments. Appears that someone used "Volatile" instead of "Vapor".
I have ordered mine from Smith & Wesson Customer Service. It appears that it is also available from Amazon:
I don't use it. I keep all of my firearms in my safe. Other forum members use other approaches, i.e. gun socks.
Welcome Aboard and welcome to the Smith & Wesson Forum!
Bill