This grill matches the HiFlo Lite Fan Units and is perfect for mating with the fan units for added airflow or for simply increasing natural airflow.Installation-1.Determine the location for the grill ensuring that there will not be any obstructions inside the cabinet,2.Cut a maximum hole size of 4 W x 3.5 inch H (10cm x 9cm) opening in the cabinet - using a jig saw would be most appropriate,3.Using the grill as a template, mark the 4 screw holes and pre-drill those with a small drill bit (smaller than the screws),4.Screw grill to the cabinet.