Kosar invented a thermal bag used to keep pizza warm. She launched her insulated pizza bag company, "Thermal Bags by Ingrid", in 1983. She ensured the bag was big enough to hold multiple cartons, flexible enough to handle without difficulty, and able to endure any spillages. Her 1984 patent application describes the bag as "soft-sided thermally insulated carrying cases". The bag combined a breathable, food-safe layer of polyester, 1,000 denier Cordura nylon and a thin nylon lining. It incorporated Thinsulate fabric. The breathable layer ensures steam can escape so that the crust stays crispy. Domino's Pizza were Kosar's largest customer. The same bag technology was used by NASA, who deployed the bag in outer space to study crystalization. It was listed as the world's largest pizza bag by the Guinness World Records in 2000.
