This little gadget is also, misleadingly, known as a "Flavor Savor". If you have trouble handling any amount of heat, this product puts about a 1cm distance between the foil and your coal allowing for a softer session - at the cost of cloud thickness and flavor intensity. The same effect occurs when you underpack your Shisha or simply use lower heat (or fewer) coals.
Note: No, it does not magically save flavor. It reduces heat going into your bowl.