Specification - T1200-F - Frame and Grate Systems MIFAB series T1200-F-4 12in wide steel frame and grate system. Lacquered 1-7/8in x 1-7/8in x 1/4in welded angle iron steel frame with anchor tabs located every 20in for anchoring support. Standard 24in long, ANSI rated "Special Duty" lacquered ductile iron heel proof grates with a safe live load of over 10,000 lbs.