This Winc Earth™ A4 Insert Binder features 2-D rings, 50mm diameter in a capacity that holds up to 300 sheets of office paper. Made with a heavy-duty board for added strength and durability. The polypropylene cover is glued to the board instead of welded, this removes all air between the polypropylene and the board and thus eliminates the chance of crinkling. A business card slot is also included on the inside front cover. Each binder features a clear insert pocket on the front and spine idea for presentations and conferences. Finding the Right Filing Capacity: Binder capacity is based on the measurement of the ring size, not the spine width of a binder. Simply measure the diameter of a ring fitting from the inside top of the ring to the inside bottom ring for the right binder to suit your needs. A4 Binder size measures 262(L) x 76(W) x 315(H)mm. Assorted colours in White, Black, Blue and Red. Select binders with 2, 3 or 4 D-rings. Available ring sizes in 19mm, 25mm, 38mm, 50mm and 65mm diameter.