With condition being such a crucial part of collecting cards, you need to protect yours in any way you can. Several supplies help you do this.
Penny sleeves are cheap and transparent plastic sleeves that guard your cards against surface damage. They’re fine for semi-valuable cards. However, they don’t provide the impact resistance needed to protect your most valuable items.
Binders, top loaders, and one-touch storage cases provide more protection. They can also prevent your cards from bending or folding, which penny sleeves don’t do. As a general rule, use penny sleeves for less valuable cards and invest in stronger storage options for your high-end cards.