Q: What does Pressure-Over-Product (POP) mean?: PASE Group, Inc.'s unique Pressure-Over-Product (POP) filler design eliminates the need for manifolds and proportionally controlled valves upstream of the fill heads. This system produces more than double the output of machines with manifolds. With this design, the feed pump runs continually maintaining a consistent level in the tank, even during container transfers. Also, because the flow out of each head is consistent, the fill weights are more accurate. Each head/scale is independent from the others, therefore when one reaches the desired weight, it shuts off without affecting the flow characteristics to the other heads and scales.