This product's classroom-tested, kid-selected flash card size invites learners to pick up, play and learn. The set includes 169 flash cards for every operation and all number families, 0-12. Each two-sided flash card has a colored border, rounded corners for durability, a pre-drilled hole for the storage ring and bold black numbers on a crisp white background. A self-checking answer to the problem is on the reverse side. The UV-coated cards measure 2½" x 4". Two sort-and-store rings are included with every set.