Durability and style-that’s Integrity from Marvin. Featuring the strength and beauty of Ultrex® pultruded fiberglass construction, Integrity fiberglass windows come in full line of popular styles. All Ultrex windows look incredible and their 100% fiberglass construction outperforms and outlasts vinyl, aluminum and composite materials. Wood-Ultrex windows combine an authentic wood interior with a virtually indestructible fiberglass exterior. There is no doubt Integrity windows are Built to Perform®.