A diffuser is a required option for the KFUH heaters. Several options are available. The KFUH-90D is a right angle diffuser featuring a 90° hood and adjustable louvers. It is attached to the front of the heater. The adjustable louvers provide you the opportunity to direct the heated air where you want it to go in your space. Since the KFUH heaters are usually installed high up, typically you would adjust the louvers at the time of installation.