Hmmm, one wonders, why does one need a clear plastic cap?
I suppose, one thinks that seeing if there is a surprise waiting, before removing the cap, might be a good idea.
There is always a surprise waiting behind mine, the only question is how much. It's just a trickle, caused by motion of the coach draining the low spots in the waste lines. Probably a few ounces, but seems like a lot more once it has hit the ground.
So I'm not sure I really get the point of having this. I mean, you're going to have to remove the cap regardless, so why not just loosen the hose cap which will at least keep the stream to a minimum of mess?
Now, clear elbows are a thing to be loved. Wouldn't be without that.