1250 Series Acoustic Slider Operable Windows from Oldcastle BuildingEnvelope™ are high-performance and economical sliding windows ideal for institutional and residential construction. Not only for use in high-noise areas, the very light sashes are ‘friendly’ to the elderly, and very easily lifted out for cleaning. Sashes can be easily cleaned and repaired. Acoustic option uses different glass combinations and other sound-attenuating modifications to achieve mid-40 STC ratings. Popular for school retrofits, glass replacement is easy and inexpensive; the building remains enclosed even when one run of sashes is removed. This very versatile systems mulls with fixed and paneled windows, and offers a very wide range of options, including deeper frames and panning trims for retrofits, extruded corners, and much more.