Rubber sheets are rubber molded into flat sheets with an even thickness. They are often sold on a roll of a specific length for easy handling. Common thicknesses of rubber sheets vary from very thin to very thick. The thickness of the sheets combined with the type of rubber used in the sheets determine their use. One of the many uses of rubber sheets (as well as reinforced rubber sheets) is for gaskets cut in different shapes. The gaskets cut from rubber sheets keep fluids and gases from penetrating substances or keep them contained within vessels or high/low-temperature mechanical systems.