Really Useful Box Storage Extra Strong 84 Litre White Polypropylene 440 x 710 x 380 mm. This storage box is perfect for storing up to 84 litres. Made from a special grade of high impact plastic, this box is even stronger than a standard Really Useful Box. The lift-off, locking lid ensures contents don't get dusty or spill out. External dimensions are 710 x 440 x 380 mm (D x W x H), internal dimensions are 605 x 370 x 355 mm (D x W x H).