The shape of Stax is a simple curve called a hyperbolic cylinder, while Pringles are formed into a double-curve known as a hyperbolic paraboloid. Stax have the flavoring spread across the inside curve of the chip while Pringles have them across the outside curve. Stax are packaged in plastic canisters [1] while Pringles are packaged in canisters made of cardboard and aluminum.[3]