Integrity From Marvin. All Ultrex windows are now available in round-top styles. The windows are made with a glass-reinforced composite material that is virtually indestructible, the company says, and they are Energy Star-rated. The round-top windows come in stone white, pebble gray, cashmere, bronze, evergreen, and ebony exterior finishes. 888.419.0076.www.integritywindows.com.