Vacuum chambers are for removing air from high viscosity materials like silicone rubber before pouring. They are also ideal for vacuum degassing liquid plastics such as Crystal Clear® plastic for making bubble free castings. Available in 1 gallon and 5 gallon sizes, the larger vacuum chamber is made from tough aluminum, the lid is made from shatter resistant acrylic and features a rubber gasket that creates a positive, air tight seal for maximum vacuum. It can accommodate up to a 5 gallon pail. Vacuum pump not included.