Name：	Outward casement window with vent
Range：	UPVC windows&doors
specification：	This vent is a built-in type. Outer. aluminium box, no protuberance. There is control unit in the profile. Special design promises air flows from down outdoor into upper indoor. Inner side is like a mesh which can prevent insects from entering in. Natural and even ventilation and air changing while no need to open the window. Especially suitable for sliding windows.