Portfolio 23 x 32 cm, with flaps to keep documents from sliding out. Large enough to hold A4 sheets without folding or creasing. It will expand to 2 cm thickness. 

Covers are the Pinecone pattern from Cambridge Imprint, which you can buy from their wonderful paper shop. 

The portfolio has a robust construction with the spine and flaps made using library buckram - a very durable bookcloth.