These Pro-Mold Magnetic Card Holders have a recessed area that is large enough to accommodate the included, specially-sized sleeve. These sleeves are an added layer of protection for the enclosed card. This is especially important if you are protecting a shiny foil card, as the foil layer can get scratched if dust was on the card when it was placed in the magnetic. Using a sleeve minimizes the chance of the foil card getting scratched. There are many branded and hobby community names for these reflective foil cards, including: Chrome (Topps Bowman), Refractor/Superfractor (Topps), Optic (Panini), silver, rainbow, reflective, holo, Prism (Panini), Pulsar (Panini), colored refractor parallels, and more. These “second generation of magnetics for sleeved cards” have arrowhead corners for the extra protection of the card’s corners.