Insul-Tec 520

  • uPVC fusion welded beveled frame & sash for strength and durability.
  • Heatseal® warm edge spacer system for excellent thermal efficiency and drastic reduction in the possibility of condensation on the inside of the window.
  • Full integral interlock with double weather-stripping. Heavy gauge fully extruded handle on bottom sash.
  • Fiberglass mesh half screens standard on all windows.
  • Available in Replacement and New Construction applications.

The most important features of Insul-Tec 520

Our company offers 2-lite and 3-lite (shown) sliding windows.
Full 3¼” Depth uPVC Fusion Welded Frame and Sash with beveled colonial exterior features curves that are not only beautiful, but also allow for maximum weld surface resulting in strength and years of long-lasting performance.
Our window opens easily because it is mounted on brass wheels which allow the slider to glide across its track.
Push Button Spring-Loaded Vent Latches allow both window sashes to remain partially open for ventilation.

Interior Options

Our company offers five beautiful interior laminates in addition to the standard Euro-White to match any decor and style.
All options, besides Euro-White, are available at an additional charge.

Exterior Options

OKNA Windows offers seven exterior stock color selections in addition to the standard Euro-White option to give your house a distinct look and enhance its curb appeal. You can also select custom exterior colors from a virtually unlimited selection of paints. Our paints are environmentally safe and durable, giving your exterior a vibrant and long-lasting color finish.
Exterior colors other than Euro-White must have full screen. All options, besides Euro-White, are available at an additional charge.


To create a style and finish that reflects your unique taste, our hardware is designed to harmonize with our different window styles and decor ideas.


GBG (Grids Between Glass) grilles consist of aluminum bars sealed in the insulation airspace between the two panes of glass. Because the interior and exterior glass surfaces are not affected, cleaning your windows is a much easier task.

Grid Patterns

Are you looking for a stunning design detail to instantly set your home apart both inside and out? A choice of decorative grilles for your OKNA Windows & Doors can highlight the architectural style that speaks to you.

Glass Options

OKNA Windows offers textured glass in a variety of distinctive choices that add visual interest to any design while offering variability in light control. With a range of options at your fingertips, you can find a standard glass texture for virtually every application and aesthetic, from traditional to modern.

Regular Obscure


OKNA Windows offers factory-installed half screen with heavy-duty handle. Screens are removable from the inside for convenient storage. We also offer ThruVision Screens improving view thru the window protecting interior from insects and allowing perfect ventilation.
ThruVision Plus is our fiberglass visibility screen that improves the view by making it sharper and more vivid.