SPECIFICATIONS GABLE LOUVER GLFF1212WH-1/8 28 Gauge Galvanized Steel · N.F.V.: 63 sq. in. • 1/8 in. Screen • Rough Opening: 12 ¼ in. x 12 ¼ in • Polyester Paint Finish 12 in. 30.48 cm 12 in. 30.