Welcome Craig, to a new type of waterless P-trap. Actually, it’s best described as a waterless sanitary waste valve. I've mentioned this device in previous posts and they're being found on more RVs directly from the factory. It's called the HepvO valve, and it eliminates the need for a bulky P-trap hanging down below RV sinks or below a shower/tub enclosure.
During manufacture, this maximizes the ceiling height in the shower area so there's no need to have that bubble skylight in the roof any more since the pan can be installed directly on the floor with the drain plumbing below. In the aftermarket, the HepvO valve will provide owners more under-counter storage space. Additionally, it does not require RV anti-freeze during winter prepping, or any maintenance for that matter.
It can be installed either horizontally or vertically, thereby maximizing installation options. This new design also has proven to be hygienically safer since waterborne food particles and debris cannot become trapped inside or given a chance to develop microbiological and bacterial growth.
Check out this RV Doctor video: http://goo.gl/aOuqTP