And Paul, without having to take the rods out to test what will fit, if you know the length and width of the box, just add the square of the width to the square of the length and take the square root of the answer. Example truck box is 7' long ..squared is 49. Width is 4'...squared is 16. 49 + 16= 65 The square root of 65 is 8.06225774829855. So the hypotenuse or the distance from one corner of the box to the diagonally oposite corner is 8.06225774829855 in other words, an 8' rod will fit in there.