Built to perform.® More strength, durability and performance are offered by Integrity® from Marvin All Ultrex® Series. With an exterior and interior of Ultrex, a pultruded fiberglass material that outperforms and outlasts vinyl, this series is everything you want plus the reputation for quality from Marvin Windows and Doors. The All Ultrex Series is easy to order, simple to install, delivered on time, energy efficient and extremely well built so you'll have virtually no call backs. Take performance to the next level with Integrity from Marvin, All Ultrex Series.