The Mason Cash Innovative Kitchen Baking Stone/Proofing Lid can be used as a baking stone for bread and pizzas or as a lid when proofing dough. The unglazed terracotta baking surface draws in moisture for crispier crusts and pizza bases. The clever 2-in-1 function means this product can also be used as a proofing lid and will fit all Mason Cash Size 12 mixing bowls.