Fire Bricks from Hifire ,Golden, DFC Duralite, Mofline, and others. Collectable as well as functional usable I have approximately 450 used but in good shape some are stamped with name. Dimensions are 9 inches x 4 and 3/8 inch's x 2 and 1/2 inches. 1-10 $12.50 each, 10-110 $10 each, 110-225 $750 each, 225-450 $5.00