E-Shield is the first fiberglass window to achieve an AAMA Heavy Commercial rating. The E-Shield window system is available with U-Factors as low as .25. The window system combines great looks (including multiple exterior color options), superior resistance to corrosion in harsh environments and industry leading thermal and structural performance. E-Shield is the first and only heavy commercial window system to use an advanced fiberglass pultrusion process. Not only does fiberglass pultrusion result in superior thermal energy efficiency, but also low embodied energy (the amount of energy consumed during manufacturing) and excellent sustainability, creating better environments inside and out. The E-Shield window can contribute to qualification for LEED certification and compliance with a range of energy codes.