The advantages are simple, beautiful, large window width, large glass block, wide field of vision, high daylighting rate, convenient glass cleaning, flexible use, safety and reliability, long service life, opening in a plane, less space, and convenient installation of screens. Sliding windows are the most used. The disadvantage is that the two windows cannot be opened at the same time, at most they can only be opened halfway, and the ventilation is relatively poor; sometimes the airtightness is also slightly poor.
This is an aluminum alloy and plastic steel window that only appeared later. It is a new form developed on the basis of casement windows. It has two opening methods, which can be opened horizontally or pushed away from the bottom. When the casement window is closed, push the lower part of the window outward to open a gap of about ten centimeters, that is, the window can be opened a little from below, and the opened part is suspended in the air and fixed with the window frame by hinges, etc. Known as the top suspension. Its advantages are: it can be ventilated, but also can ensure safety. Because of the hinges, the windows can only be opened with a seam of ten centimeters, which cannot be reached from the outside. It is especially suitable for use when there is no one at home. This function is not only limited to casement windows, sliding windows can also be opened up-hung.