Will (and others); PVC (polyvinyl cloride)is a chemical that is added to plastic to make it soft and pliable ... which is o.k. for certain uses.... like pool inflatables.

However, a chemical reaction to the pvc occurs when the plastic comes in contact with certain objects, such as metal coins and tokens and some chips with red dye. This reaction takes years to develop ... and by the time it does, the housed object which it was designed to protect has already been damaged. I'm sending you an email with a attached sample of what occurs when this happens.

Non-PVC holders on the other hand are usually stiff and brittle, which is why some collectors don't like to use this product, especially if it gets a lot of use in handling... in and out of album pages, etc. Some collectors also prefer to deliberately break the stiffer non-pvc flips into two halves and use them that way.... maybe as an economy measure ... and maybe because they prefer not to take chances with the pvc flips. A half a non-pvc flip is better than a whole flip that contains pvc.

Metal tokens are more apt to be damaged than chips as time goes on and the pvc breaks down and causes bright shiny surfaces to dull and become sticky from the gooey plasticizer decomposing. Unfuortunately, by this time it's too late. No amount of dipping will restore the once-brilliant reflective surface of a pvc coin or token.

It's always a good idea to periodically check your tokens and chips that have been stored in vinyl flips for a long time. Sometimes it takes an unfortunate personal experience to believe it. We all learn by our mistakes.

Hope I've answered your question.