The all-welded 4000 series are our performance-grade windows that offer great energy advantages and structural integrity with an upscale architectural appearance. This has a welded sash and welded frame, giving it a high level of durability that will last for years. The 4000 series architectural look and durability will enhance a residential project’s aesthetic for years to come. From its sturdy construction to its energy-saving performance, the 4000 series is a true workhorse of a residential vinyl window and is perfect for homeowners seeking to upgrade their property. The 4000 series meets both housing authority regulations and Energy Star requirements. This welded vinyl windows series includes Single Hung, Picture, 2 Lite Slider, and 3 Lite Slider window types.