China factory Aluminium Frame Casement Window 1.Sliding flexible/durable hinge, can resistance typhoon if adopt high slide rail. 2.Extra special waterproof and airtightness treatment. 3.Double hollow glass,nice heat and sound insulation. 4.Decorative bar design available,anti- theft. 5.Nice EPDM sealing performance. 6.Economical,nice price performance performance.