Made of 100% 304 stainless steel 16g welded wire and J-clips. The EVG4.0 is designed for damper-style exhaust vent covers. Inside dimensions: 6-1/2”h x 6-1/2”w x 4”d. One-inch fastening flange. Always check local building codes. NOT for use on dryer vents. Quality add-on for increased revenue!