Pella Corporation 
The revolutionary, award-winning Pella® Impervia® product line, manufactured from Duracast® — the strongest, most durable material available in windows and doors — is now available for non-residential and multi-family projects. Pella’s exclusive five-layer Duracast fiberglass composite material offers the durability of aluminum, the energy efficiency of wood, and a price that is competitive with vinyl.
4specs Discussion Forum - Great place to ask questions about specifications, products and technical data. Free - no registration required to read or post (subject to moderation).
See also: 08 1580 - Plastic Windows (Residential & Light Commercial) - primarily vinyl
Pella Corporation
The revolutionary, award-winning Pella® Impervia® product line, manufactured from Duracast® — the strongest, most durable material available in windows and doors — is now available for non-residential and multi-family projects. Pella’s exclusive five-layer Duracast fiberglass composite material offers the durability of aluminum, the energy efficiency of wood, and a price that is competitive with vinyl.