Difference between jebao auto doser versions?

[LMuhlen]

I'm casually looking at auto dosers, cheap ones, and there are a bunch of jebao models.

Does anyone know the difference between the 2.X, 3.X and 4.X versions? I think the 2.X doesn't have wi-fi, but I can't find what's different between the newer models.

I'll take suggestions for other brands as well, in the same price range.

 

[LightingBamboozled]

2.4 has wifi and manual, 3.4 is wifi only. I've never seen the 4.4.