UPDATE: We're now pretty confident we've identified which models have one waste ink tube and which have two so as a quick rule of thumb: G series model numbers are formatted like this: - G[Series][Country_Code][Model][Sub-Model] So a G4210 is a 4000 series, North American, 10 model With this in mind, model types determine whether you have 1 or 2 waste ink tubes. Model: 0 => 1 waste ink tube Model: 1 => 2 waste ink tubes So to take our earlier example, the G4210 has 2 waste ink tubes. Hope that's a bit clearer.