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 degrees Fahrenheit, 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 square inches net free area Heavy-duty aluminum mesh screen, front and back