Comments about Photogenic Photogenic 7-1/2" Fine Honeycomb Grid for the PowerLight Monolights. (PL7GF):
You do need the PL7MF to use the PL7GF properly. The PL7MF mounting frame holds the PL7GF grid far enough away to let air circulate around the modeling light and flashtube so that heat can escape from in front of the light.
Without the PL7MF the grid will not attach to the powerlight.