Multiple Glass Options

Low-E Coated Glass
Low-E glass is coated with a microscopic layer of silver that reflects radiant solar energy while permitting visible light to pass through the glass, providing more comfort and lower energy costs.

Standard Low-E Glass with Argon Gas
Argon gas works like an insulating blanket between two panes of glass to further improve thermal efficiency and decrease outside sound levels.

Ultra Low-E Glass with Argon Gas
Choose our ultimate glass package for optimal energy efficiency and maximum cost savings. Ultra Low-E glass offers three invisible layers of silver coating in addition to the superior thermal performance of argon gas.

Triple-Pane, R-5 Compliant Glass
(available on Series 3900 only)

Triple-pane, R-5 compliant glass with Super Spacer® sealant system provides industry-leading thermal resistance, noise reduction and protection from the sun. The Series 3900 offers this option with both Low-E glass with argon gas or Ultra Low-E glass with argon gas, for the ultimate in insulation.


InsulKor technology is a system of sash and frame enhancements that dramatically improves the performance of the Series 3900 double hung window.

Advanced Series 3900 Features

  1. Optional InsulKor multi-cavity foam-filled frame injections
  2. Super Spacer® sealant system (standard with Series 3900 triple-pane glass options)
  3. Triple-pane, R-5 compliant glass


Low-E and Argon for WeatherLok Windows

Understand Window Condensation

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