The panels are first snapped together on the long side, and then the straps are attached to the pins using the perforations and forming a variable spacer bar to hold in position a zig-zag fill pack. The zig-zag pattern is either held in an opened pattern or more closed, depending on which series of holes are selected in the spacer strap.
In this way the panels may be used to create customised fill packs to a variable "density", yielding the required cooling coefficient. The size of the pack module that is produced is 60 cm wide by 30 cm high by whatever length the zig-zag pattern is continued, (often 120 cm). Fill modules are placed side-by-side to cover the total floor area of the tower, and then stacked on a second level alternating length for width, to make a double level (60 cm high), or a triple level (90 cm high), etc.Panel configurations have been developed that are ideal for both cross flow and counter flow towers. Widely spaced configurations are best for dirty water conditions. Tighter spaced configurations are best for achieving a minimum approach temperature.