Extension box #22A
271 blocks with construction manual #24, section plans #24 and packing scheme. To be used in connection with the following boxes: 6 + 6A + 8A + 10A + 12A + 14A + 16A + 18A + 20A OR 4 + 4A + 6A + 8A + 10A + 12A + 14A + 16A + 18A + 20A.