Select Clear Choice® mortar-less glass block window systems for a dramatic effect. More vibrant and light emitting, block made of real glass stays clear, won't yellow or discolor with age. The preferred Thinline series delivers the strength and beauty you expect, without the weight of standard 4" depth block. Available in several patterns and frame colors to complement any color scheme. Our Wavy Mist® pattern is the newest addition to Pittsburgh Corning's collection and is an excellent complement to current architectural expression.