The first time I noticed this is in an activity above, because the budget is limited, so everywhere contrast everywhere, just see here have activities, think fine workmanship, and finally bought aluminum clad wood inverted sliding window,
Home balcony towards the north, the balcony after sealing up the winter is not cold, sound insulation is good, the window is closed, the downstairs dancing sound basically can not be heard, and now used for more than 3 years!