The external windows in the building construction are used for ventilating and lighting, which can be dated back to the ancient times. Such construction elements have been also imbedded with another function of decorating and embellishment in current days. In 21^st century, the traditional function of

the construction has been altered from constructing to making and as a part of it; the windows and doors are also making changes. They are changing

from assembling on site to assembling in the factory. And the whole construction process is tended to be more integrated.  

The subframe window will adopt the heat tensioner which uses the nylon materials to block the heat bridge between the bolts and the frames and

adjust the gaps in the fixed position of the frame to assure the quality of the fixed bolts. The windows without the subframe will use the

pressed putlog coupler which will be fixed on the out frame. The pressed coupler will be pushed into the fixed grooves to clamp the bolts. Then the

whole window frames will be more tough and stable.