Edges and Corners Included!!! ~~~ 0.4" Thick Foam is Safe for Babies of All Ages Conforming to All Required Safety Standards and Insulates From Cold Surfaces * The 12" Soft Foam Squares Provide a Colorful, Washable, and Durable Surface * Includes 36 Colorful Pieces with 26 Uppercase Letter Mats and 10 Number Mats (A-Z, 0-9) * Made from Safe, Non-Toxic High density EVA Foam Bright Pastel Colors For Child Comfort * Each Individual Mat Measures 12" x 12" (inches) ~~~ Covers up to 36 square feet (6" x 6" area)