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. thanks for looking

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