With 18 in lintel for new construction. Fits standard 8 in x 16 in vent openings. High-density thermo-plastic construction. Automatically opens at 70 deg F, closes at 40 (approximately). Key working mechanism, bi-metal coil, fully enclosed by protective cover. No electrical hook-up required. Stainless steel and corrosion-resistant metal parts. 62 sq-in net-free area. Heavy-duty aluminum mesh screen, front and back. 8 in x 16 in.