Cake Box - Extension Corner Cards (10"/254mm) (2 ratings) Cake Box - Extension Corner Cards (10"/254mm) for tiered cakes £3.75 To accommodate taller cakes! Folds to 5'' (76mm). Suitable for use in boxes up to and including size 13''. Specially sized extension corner cards to fit into white cake boxes. Packed in sets of 4, each card sits neatly into the corner of the box to extend the height of your white cake box to 14'' (355mm). Shrink wrapped for hygiene. NB:Extension corner cards can also be used with the heavy duty boxes, however the drop down side would have to be taped up. (Boxed 4).