This Pella 250 Series sliding window measures 45 x 45 inches and is in like-new, in-box condition. It is a left-hand operating slider (OX configuration — one fixed, one venting panel) with a white vinyl frame and includes the original screen. The glass is annealed Low-E with a slight tint, argon gas fill, and is rated for high-altitude installation. Solar heat gain coefficient is 0.21 and visible transmittance is 0.50, making it a solid energy-efficient choice for Colorado climates. No damage or missing parts reported.