Marvin offers a range of standard, performance and specialty glass options:

(*) Performance Glass Options
(*) Glazing options such as LoĒ²-272® and LoĒ³-366® enhance energy performance.
(*) Tripane glazing, available with argon or krypton gas, provides excellent energy performance.

Tripane features two coated panes of glass with a third pane spaced between them. It’s available with LoĒ²-272 on both panes, with LoĒ-180 on both panes for high SHGC, or with LoĒ³-366 on the exterior pane and LoĒ-179 on the interior pane for low SHGC.

Tempered and laminated glazing options are available to meet special safety and impact requirements.

http://www.marvin.com/windows/wood-casement-windows/glass-energy-efficiency-and-screens/