Abstract: A box disposed in a car trunk includes a bottom, two opposite first walls and two opposite second walls, the bottom having at least one slit defined therein, each of two first walls having a protrusion extending from an inner peripheral surface thereof and the protrusion having a first hole defined in a distal end thereof for a first separate board pivotally engaged between the two protrusions wherein the first separate board is positioned by inserting an inserting plate extending from an lower edge of the first separate board into the slit, each of the first walls and the second walls having a flange extending transversely from an upper edge thereof and a first position hole defined in the second walls near the flange and a second position hole defined in the flange corresponding the first position hole, a sliding member disposed to each of two ends of the first separate board and engaged with the second position hole via the first position hole, at least one second separate board disposed between the second