Even for casting, if you have eg cooked his potatoes or pasta, the part is not bad. Simply put, hold and then pour the pot carefully onto the pot. The content remains in the pot, the water is poured off clean. But here this is already handled with caution, as it is easy on the fingers can scald boiling water or steam to the hot.
As backing for hot pots but I do not use the disc. It is in a thin silicone disc with holes, and I am afraid that the heat still pushes through the holes and then eg ruined me the tabletop. The specified function as a support in the oven, for example for a frozen pizza, I do not use because of the simple baking sheet I get here anyway towards an excellent result, having to push without a piece of silicon plastic in the hot oven.
As protection from splashes, however, the actual use, this part is a real relief and a good gadget for the kitchen.