Drip cups are associated with Dometic Penguin A/C units. RVP-Coleman units can be ordered with a condensate pump. Both of these units channel the condensate into Airstream's drain tube that is installed by the factory and runs the condensate thru the sidewalls of the trailer usually exiting above the wheel wells.
From my experience, the Dometic drip cup system if far better than Airstream's proprietary drain pan, far easier to install and also will spill the condensate onto the roof instead of inside the trailer (like the drain pan) in the oft chance that the drain tube gets blocked.