Positively stacks with or without the lids. Strong enough to take a persons weight. Minimal wall taper to maximize storage capacity. The above feature also makes the contents less likely to move whilst in the box. Totally flat and reinforced bottom. Easy to operate anti tamper system. Locking mechanism to prevent the lid separating from the base. Available in a wide range of colors including transparent. Transparent feature allows you to see the contents. You can mix and match different colors for base, lid and handles. Some sizes have an integral lip that allows suspension files to stand up erect. Ergonomically designed. Inters tacking of the different capacity boxes. Our extra strong boxes are perfect as courier boxes for parcel deliveries or airfreight.