The motion is enabled by two counterbalances, which happen to be both created in to the body or inside the window. This type of window is also known as a box sash, as the mechanisms are encased in just a concealed box that’s created into the perimeters in the windows. https://cosmetic-ipl-laser-gel82580.ivasdesign.com/56882826/5-simple-techniques-for-sash-window-draught-proofing