The basics done better, JELD-WEN V-2500 Series Vinyl Windows are made to be durable, energy efficient and attractive for many years to come. This sliding window has two sliding sashes that slide alongside a fixed sash in the middle of the two operating panels. Nail fin frames are ideal for new or replacement construction in a typical wood frame structure - commonly referred to as stick-built construction. Nail fins can be easily removed for pocket or block frame installation into wood, concrete or masonry walls with little disruption to the interior and exterior trim. Coated with a microscopic silver layer, LowE insulating glass lowers energy costs and helps homes stay cooler in the summer and warmer in the winter by reflecting sunlight away from the home in hot weather and heat back into the home in cold weather.