The Original Adapter is used to adapt to various exhaust fans in the industry. For best results, grease should be directed to fall into the middle of the filter/pillow. The adapter allows grease to get past the fan base to hit into the grease containment system. Used as a spout replacement for fans with no spout or missing spout. Flat sides are designed to be formed to shape around the fan base prior to installing screws. 1-1/4 Inch Diameter NOTE: in some cases, hose extensions are needed. These adapters are also used to plumb the DRIPLOC Pail Filter System. WARNING : This product can expose you to chemicals including Cobalt Metal Powder and 1,3,5-Triglycidyl-s-triazinetrione, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov .