-The sealed drain system and dry fixed construction has the excellent airproof and waterproof ability. -With variety of opening ways and optional aeration and the degree of the opening. -The glass can be taken down easily at room, which make the maintenance and glass-change convenient, in addition to the colorful decoration. -Safe and convenient opening of leaf, and it can be cleaned easily. -Carrying the equal size room theory obtain the excellent hear-preservation, sound insulation and less-transfiguration ability the superiority is fit for the large grille. -By using the 20mm insulation bar and improve the heat-insulated and heat preservation ability of series 60.