out-open or up-hung window

The outside surface of leaf and frame as well as the inside ones are at the same plane ;
*The fixed leaf and active leaf can be exchanged freely
*With smooth junctionÿ¢firm connection and tidy assembly;
*Double-sealed insulating glass;
*Sealed drain system with excellent anti-air and anti-water ability;
*Need less profile and be economy in actuary;
*Obtain the large lighting area and with bright effect;