Basic Cardboard Blocks (Set of 40). 2 years & up. These 40 sturdy cardboard building blocks are lightweight and strong. Easy to assemble, brightly colored, and easy to stack to make endless building combinations. Includes 3 different size blocks with the largest being 12"L x 6"W x 3"H. While we aim to supply accurate product information, it is sourced by manufacturers, suppliers and marketplace sellers, and has not been provided by Overstock.