These filters, commonly known as “Fire Patrol”, are made from 430 Stainless Steel. The unique roll formed baffles are designed to collect grease and prevent flames from passing through. The maximum operating temperature is 700 degrees F. They are UL classified and meet NFPA standard 96.
430 stainless steel is not quite as corrosion resistant as 304 stainless steel but it is shinier and if aesthetics are considered, this is the one you want.
All standard sizes are undersize 1/2″ on width and length and 1/8″ on thickness. Custom sizes are +/- 1/8″ on width and length.