Our Letter Size PIP boxes are available in white Brown and premium white. The Premium white are Self seal and easy to assemble which saves Time and Money when packing large numbers of orders, these boxes are designed to be letter size which means when you send these out with Royal Mail they will always be charged as a large letter. These are available in A4, A5 and A6 sizes so we have all the sizes available. The C4 size will fit our 10×14 Mailing bags which is perfect to give it extra protection. Many customers also use our Kraft paper tape or our Stick address labels to secure it further for peace of mind.