Foldable cups fit in your pocket. Collapsed they are less than 2 cm thick. Made of BPA-free food-grade silicone, with nylon rings to maintain shape and protect fingertips from heat. Base, rim and center ring made of lightweight yet durable glass reinforced nylon 66. This space-saving 355ml mug weighs just 54g, taking lightweight functionality to a new level. It coordinates with other Frontier cookware and with the 2 litre pouring pot.