Durable & Customized uPVC Sliding Window. Duroplast offers High Quality Sliding Windows in various designs i.e. Two Track, Three Track & more . Sliding Window comprises of two or more sashes that slide horizontally on the outer frame. The sashes move smoothly on the outer frame with the help of nylon rollers, when compared to aluminium and other traditional sliding windows. Multi-chamber design of the profile reduces the transfer of the heat thus saves energy. All the sliding windows are steel reinforced for added strength Sliding Windows are incredibly functional and one of the easiest type of windows to use. These windows ensure more light and air to come in.