Personally, I like the cardboard fold-over type holder with the clear mylar window for long term storage protection. Mylar is inert and has no platicizers and they are relatively inexpensive to purchase. Some people don't like the staples used in this type holder as it makes it very difficult to remove the chip once it is stapled on all three sides (with the fold at the bottom) ... unless you only place one staple at the top of the holder leaving the sides open for chip removal. Just a matter of personal preference. Most folks don't carry staple guns with them at chip shows, so the ease of using the vinyl flips temporarily is very popular. If you purchase a package of 100 vinyl flips for long term storage, make sure the package says "PVC Free". BTW: PVC stands for polyvinylcloride.