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We stand firmly behind the quality of all OKNA 820 Series windows we install, and would easily compare them to premium brand windows costing two to three times as much.   Our 820 Wonder Choice windows have become increasingly popular in the past few years, due to their stylish appearance, reliable weather resistance, leading energy efficiency and overall value.

OKNA 820 Sliding Window

OKNA 820 Series

  • Perfect as replacement windows or in new construction projects
  • Carefully designed to work with almost any room or motif 
  • Includes standard half-screen made from premium fitted mesh
  • Automatic moisture and condensation prevention feature
  • Powerful 3.25" fusion-welded mainframe construction
  • Colonial inspired curves and bevels uniting strength and beauty
  • Designed to provide years of consistently-reliable performance
  • Multi-chambered vinyl profile for maintenance-free use
  • 820 Series windows utilize Heatseal® for improved efficiency 
  • Interlocking double-insulated weather stripping
  • Increased window security with a locking screen upgrade.*
  • Triple Pane:
    • NFRC U-Factor: 0.20   Air Infiltration: 0.05   Solar Heat Gain: 0.25
  • Double Pane:
    • NFRC U-Factor: 0.26   Air Infiltration: 0.05   Solar Heat Gain: 0.29
  • One of the most impressive attributes of the 820 Sliding OKNA windows, is the highly-elegant profile and design. It has been crafted to unite high syle, uncompromising protection and years of reliable performance.

  • The 820 Series gives your home the look of much more expensive wood windows, while simultaneously giving you the protection and easy maintenance you demand from new or replacement sliding windows.

  • Sometimes you just want to open your sliding windows just enough to let in a light breeze, without compromising safety or peace of mind. Spring loaded latches make for effortless operation and total convenience.

  • A standard slim sash profile and tamper-resistent cam design, makes the 820 series OKNA sliding windows last much longer than windows with traditional locking systems.

  • To give your new sliding windows the most quiet operation possible, special bumbers come standard on all 820 Series windows. Ask your Wonder Windows consultant why we proudly recommend OKNA sliding windows in Western NY.

  • Heavy duty rails have been specially-mounted on brass wheels, to provide effortless gliding motion that will make your 820 Series windows a joy to use!

Interior Options

In addition to traditional Euro-white, Wonder Windows offers the 800 Series windows in three additional shades. Of course, we understand that your imagination knows no boundaries, and we can custom order your new windows in literally thousands of colors. The heat reflective coatings used to custom-color your windows are environmentally safe, and guaranteed to keep their beautiful appearance for years to come.





Melrose Cherry

Dark Oak

Onyx Black

Exterior Options

Okna Windows offers six 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 exteriors a vibrant and long-lasting color finish.



Terra Brown


Basic Brown


Nicol's Black

Custom Colors


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.


Antique Brass

Brushed Nickel

Matte Bronze


GBG 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.

Permanent interior and exterior grids with spacer will provide a truly authentic look. Interior grids are available in Euro-White or wood laminates to match your home's decor. External grids are available in Euro-White or colors to match product exterior.

Flat Grid

Contour Grid

SDL Grid

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.

Obscure Glass

Niagara Glass


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 fiber glass improved visibility screen. This product does for windows and doors what high-definition technology has done for television viewing; it improves the view by making it sharper and more vivid.

Industry Average Screen

ThruVision Plus Screen

Series OKNA Enviro-Star 1800/800 Series OKNA Enviro-Star 1800/800 Series
Triple Pane Standard Standard
Double Pane Optional Optional
Model Name Super Deluxe Deluxe
Glass Panes Triple Pane Double Pane
U-Factor 0.19 0.27
Solar Heat Gain (SHGC) 0.25 0.29
Visible Transmittance 0.41 0.52
Condensation Resistance 72 63
Design Pressure DP50 DP50
Structural Performance R50 R50
Air Infiltration 0.05 0.05
Foam-Filled Frames Yes Yes
Screen ThruVision PLUS ThruVision PLUS
Manufacturer's Warranty Lifetime Lifetime
Our Labor Warranty Lifetime Lifetime
Glass Breakage Free Free
ENERGY STAR Most Efficient Yes* Yes*

*with triple pane glass

All results numbers based on tested window sample by NFRC and AAMA testing guidelines.
Used for comparison purposes only. Actual values may vary depending on installation, size of the window and other conditions

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