Laurel, MD – Vytex Windows, a custom manufacturer of energy-efficient, vinyl replacement windows and patio doors, recently expanded its window offerings to include the all new Fortis Series®. This Series offers an R-50 DP Rating and an air infiltration rating of 0.05 cfm/ft2. The main frame sill has 3 sealing locations, including a structural sill interlock that nests into a receptor on the bottom sash. This coupled with a frame sill dam that is mortised behind the jambs provides for increased structural integrity and decreased air and water infiltration. The Fortis Series® comes standard with VyCore™ insulating foam in both the frame and sash members as well as ThermaCore™ Composite Reinforcement in the meeting rails. The standard dual pane Low E/Argon double-hung unit achieves a 0.26 U-Value, with U-Values as low as 0.16 in a triple pane configuration. A Fortis Series® option is an R-5 dual pane insulated glass unit that does not employ hard coat Low E on surface number 4. The Fortis Series® utilizes a new, state-of-the-art inverted constant force balance system which provides up to a 50% reduction in operating force for smoother operation than typical balance systems. The main frame exterior offers a soft, classic architectural detail and the narrow profile interior offers a larger glass viewing area. The Fortis Series® replacement windows are also available in VyWood™ Paintable/Stainable laminate interiors as well as over 25 VyCoat™ exterior colors. The Fortis Series® from Vytex is the next generation, energy efficient window.