Corkscrew is a CBS premium dichroic coating offered on thin glass COE 90. Corkscrew fires to a vairiety of mixture colors. This coating is offered on clear and black glass in a 4x4 inch square or a quarter sheet. There are approximately 66 square inches in a quarter sheet of glass. Please Note: All photos on black glass. NOTE: EVERY SHEET OF Corkscrew IS DIFFERENT, PHOTO REPRESENTS A SAMPLE.