Square shape is perfect for square growing areas. Improved design for more efficient and even light distribution. Completely sealed?featuring hinged glass and double gasket (between glass & reflector and glass & frame) for an air-tight seal. Powder-coated galvanized steel housing with handles built in. Integrated socket & 15 ft lamp cord. Swing Stop? retention cable keeps glass from abruptly swinging down. Captured thumb screws & closure mechanism for ease of use and excellent sealing. Comes with built in level for easy, consistent, level hanging. Interior is 95% reflective German Hortibright aluminum. Integrated air-cooled fittings with a bead ring to hold ducting firmly in place! US Patents: D570,295, D634,469, D698,628, D644,185, D731,701, D747,538, 7,641,367. Chinese Patent: ZL201430019221.4.