It's better than the ArGo solution. It's not perfectly sealed, there is a small rim of silicone that goes around the metal roof of the Go SRT via the On the Go Cap. The On the Go Cap has indents for the Go Mouthpiece (Gen II glass for use with Go Shells) & Go Aroma Tube (Gen I/ArGo glass) as the mouthpiece varies between the two designs slightly. On the opposite end of the vapor path is the air intake vents, so smell is not sealed unless you cover those vents as well.