Each Contour Flap Envelope is 5.5″ L x 4.1″ W.Each Blank Single Panel Cards is 5″ L x 4″ W. Blank Single Panel Cards fit perfectly in this envelopes. Size: Each Contour Flap Envelope is 5.5″ L x 4.1″ W. Each Blank Single Panel Cards is 5″ L x 4″ W. Blank Single Panel Cards fit perfectly in these envelopes.