Tupperware Fridgesmart Small Deep Containers

I have 5 previously owned Fridgesmart Small Deep Containers from Tupperware. 4 of the containers are in great shape. 1 has some staining from being used to store tomato-based food; selling it at half price. According to Tupperware: Top food scientists from the University of Florida and Tupperware have researched the storage of fruits and vegetables extensively to develop a line of intelligent containers.​ Tupperware's ACE (Atmosphere Controlled Environment) system creates the optimal environment to maintain freshness for longer. FridgeSmart® Containers use this special three-way venting system to help regulate the atmosphere inside the container by balancing the flow of oxygen coming in and carbon dioxide going out. ​ FridgeSmart® Small Deep container has a capacity of 1¾ qt/1.8 L.