Dano...
Don't leave home with out it!
Seriously, a pumpout hose will lock onto it with no fear of blow-back or spill. I've seen the universal tapered rubber tip some pump-out locations use break suction and effluent spew all over the place and all over the boat owner holding the hose as well. I bought one the next day!
There's only two thread sizes so getting the correct one should be easy.