Product review (3 stars): Difficult to install, but works.
I could not find another choice for dual ro and dishwasher.  The clear plastic cap must go under the top nut in the proper keyed position.  Instructions recommend a basin wrench to tighten to lower nut, good luck!!  Other air gaps have the an angled nipple to the disposal.  Bending the hose the extra 30 degrees can cause a kink.