This is a new glass. Glass is 3/16 thick and about 15 1/2 wide x 11 3/8 tall ctr x 9 7/8 rt and left ends and arched on top. Yes it is heat resistant ceramic glass used by quadra fire. Part #7000-012 for 3100, 3100i, 4300 4300i and 4100 stoves. The “I” is for insert, all others would be free standing or step tops. THIS FITS THE 3000 MODEL FROM 1989 TO PRESENT. DOUBLE CHECK THE WIDTH ON YOURS! THE 1988 AND OLDER MODEL 3000 IS DIFFERENT. ITS #7000-013 IN ANOTHER OF MY AUCTIONS. 4100i is NOT the same. This will NOT fit a 4100i insert stove but Will fit the 4100 free standing step top stove. Wood Burner Stove, Mulyi fuel stoves, Pellet Stove and Coal Stove Windows. Wood and Gas Fireplace Doors. Grill Covers and Trivets. Spark and Flame Guard panels. This material is actually a transparent glass-ceramic. ROBAX® glass-ceramic has a thermal endurance far exceeding that of normal tempered glass. Tempered glass is generally limited to applications that do not exceed 500F. However, ROBAX® is designed to operate at temperatures ranging from minus 400F. Glass-ceramic was invented in the 1960s. Its thermal endurance and stability make it ideal for many products: from stove tops and cookware, to missile nose cones and astronomical telescope mirror substrates. Transparent glass-ceramic, introduced in 1970s, is much more difficult and expensive to make than ordinary glass. As a result, it also has a different appearance including color, surface texture, and some small bubbles or inclusions that are natural to its composition and have no effect on its strength or performance. Because of its special composition and processing this unique material can withstand a quench into ice water from red hot temperatures. With ROBAX® Glass-Ceramic windows in your stove or fireplace, you can enjoy the fire view with the assurance the window has been designed with a superior margin of safety for your home and your family. This is an excellent replacement in most applications for any of the following glasses – PYREX®, BOROFLOAT®, TEMPAX®, VYCOR®, PYROCERAM®, and NEOCERAM®.