The Hollow core construction makes these shelves lighter and stronger than traditional shelves. They're good to cone 10, ground flat top and bottom, more efficient to fire and cracks are less likely to travel across shelf. We only ship shelves up to 15". The larger shelves are very heavy and there is a chance of breakage during shipping. A 10% shelf packing fee applies with a minimum of $10.00. Please inspect your shelves with in 48 hours of arrival and report any damage to us. Corelite Kiln Shelf for 24" Diameter kiln (Skutt 1027, Cress E27) Full Ro 21" x 5/8" Full 98637$75.00 Kiln Shelf for 24" Diameter Kiln (SKutt 1027, Cress E27) Half Round 22 x 10-1/2 x 5/8 98650$49.00 Kiln Shelf for 28" Diameter Kiln (Skutt 1227, E28) Half Dodeca 26 x 13-5/8 98464$69.00 Square Shelf 18" x 18" x 1" 98696$65.00 Rectangle Shelf 24" x 12" x 1" 98631$59.00