The CRYPTO-BOX Memory includes a two-port USB hub with the CRYPTO-BOX electronics and the flash controller behind it. This is necessary, because the CRYPTO-BOX chip itself does not support USB high speed access.
According to USB specifications, additional USB hubs may be branched into a tree structure with up to five tier levels. The CRYPTO-BOX Memory itself already uses one tier level. Therefore you have to take care that the total number of tier levels must not be exceeded.