How Strong is Ultrex?

Marvin Fiberglass Windows – Stronger than vinyl, more affordable than clad wood, they stand out for their strength, low upkeep, and good looks. Perfect! Ultrex Fiberglass Infinity® replacement windows and doors -made from Ultrex fiberglass – a material so strong and durable it is superior to other window materials.  Most importantly, it makes Infinity from Marvin …