1) Simple structure, easy installation 2) Smooth sliding 3) Soundproof, heat insulation, fireproof, damp-proof,etc. Product Description1 ... , heat preservation and sound insulation 5 Offtering a wide choice of glass, including single-glazing, double-glazing, triple-glazing, coated ... and plastic and strong cartonBesides,we can design the style of your window frames as ordered. Windows--design insert