Eze-Lap Credit Card Fine. Diamond Wallet Sharpening Stone. Credit card size sharpener measures 3 1/4 x 2" and conveniently fits in vinyl slip pouch. Perfect for sharpening a variety of tools and household items. Fine." Fine grit. Credit card size sharpener measures 3 1/4" x 2" and conveniently fits in vinyl slip pouch. Perfect for sharpening a variety of tools and household items.