Anything where one dimension is much greater than the other two — usually 24" or more in length. The shape is the point: it keeps a narrow item from rattling around inside an oversized square carton.

Length works against you. A 48" single wall box will bow in the middle if the contents are heavy or if it gets stacked. For anything past about 36" with real weight in it, double wall holds its shape far better.

Usually yes, but often with an additional handling charge. Past roughly 96" you are into freight rather than parcel. If you ship long items regularly it is worth checking your carrier agreement before you standardise on a size.

Posters and prints, tubing and conduit, window blinds, curtain rods, trim and moulding, fishing rods, tripods and light stands, banners, and rolled signage or artwork.

Two inches of padding at each end is the rule of thumb. The ends take the impact when a long box is set down, so end padding matters more than side padding.

Tell us what you are shipping and we will help you spec it. Free delivery on Houston orders over $500, or collect it yourself at Harwin Dr.