Features: * Replaces old-style manual vents * Fits standard 8 in. x 16 in. vent openings * Automatically opens at 70 degrees Fahrenheit and closes at 40 (approximately) * The key mechanism, bi-metal coil, fully enclosed in protective cover * Stainless steel compression spring with 1 adjustable screw for easy installation * 65 square inch net free area * High-density thermo-plastic construction * Stainless steel and corrosion resistant metal parts * Heavy-duty aluminum mesh screen, front and back * No electrical hook-up required What"s In The Box: * Witten Automatic Vent 306MGR Auto Vent B-E, Gray