Heating core - distributes heat to bake large cakes evenly. Releases easily from cake. Recommended for 10 inch diameter or larger pans for complete baking. To use, grease inside and outside of core, place in centre of cake as it is baking, fill core with batter also. Once cake is cooked, remove core from cake, remove cake from inside core and place this plug, back in to centre of cake. I have used this myself, and could not believe how well it worked.