This base plate has 18x18studs on a 28.5cm x 28.5cm board. It is strong and durable blue plastic, compatible with our Educational Bricks and also with any Duplo items you already have. A top quality product and one of our best sellers. We use it for small groups and/or for a large display and storage of our educational bricks. We have also glued these large base plates to an A-frame Easel which is very popular with kids and customers alike.