The ClimateSmart 3900 Window has a 1” setback, pre-punched Integral nailing fin ensuring easy and accurate installation. 12 different chambers in this profile creates insulating pockets of air for increased thermal efficiency, structural stability, and sound control. Sash interlocks with aluminum reinforcement provides added structural strength. High-density weather-stripping blocks infiltration of air, water, dust and noise. Insulated glass with warm edge Intercept spacer for maximum energy conservation. Specially designed weep system provides proper drainage while reducing air infiltration. Fusion welded construction for consistent square corners. Various glass options including HP Integrit “E” Low E. Cam lock and hidden keeper pulls weather strip together for a positive seal, optional Self Lok 2 available. Smooth frame surfaces are a result of using stainless steel extrusion dies. Molded lift and pull rail permit easy sash operation. Innovation in the window design provides beauty, strength, and durability.