Specification - P6290 - Heavy Duty 12in Wide Stainless Steel Trench Grate and Frame MIFAB series P6290 - 12in wide heavy duty slotted trench drain constructed of 3/16in (7 guage), Type 304 stainless steel with 1-1/2in x 1-1/2in x 1/4in stainless steel angle frame. Free area of 21 square inches per 1 ft. section. Standard with ANSI rated "Heavy Duty" slotted Type 304 stainless steel grates with a load rating of 5,000 to 7,500 lbs.