To determine the caster level power of a magic device when it is unlisted, use the minimum level required to cast the powers contained within the device. For example, the rod of passage can produce teleport without error and astral travel. Teleport without error is a magic-user spell, so we can figure that the astral spell power involved would be the 9th level magic-user variety and not the 7th level cleric variety. Therefore, since an 18th level magic user is required to cast a 9th level spell, we cna assume the rod of passage operates at the 18th level of power.