I loved these when I got them initially, however, the shine has worn off since and I see some issues when the gallon just I am pouring from is nearly full. The following images illustrate the usage.
First you squeeze the jug so it can fill up the pro-blend. Here I am measuring out the Chemical Guys Microfiber wash. A very small amount as you can see.
Then you pour it out. The problem starts with this: notice how the tube (there is a tube inside connecting the bottom of the dispenser and ending at the bottom of the jug) is still immersed in the liquid. Since this pro-blend has no controllable valve, as long as the tube can pick up liquid it keeps on pouring it out. Speak about unbounded measurement error! Epic failure of duty!
As you can see, I have tried to minimize this by pouring it out in an awkward angle (instead of holding the handle above the level of the dispenser), however, the tube in my case is still not empty of fluid till I tilt the jug level: by which time most of the liquid in the tube has already flown out, once again messing up my calculations. Atleast now, the error is minimized to the volume container in the tube. Still, Incompetent design! to say the least.