Gro Pro? Super-Duty Saucer/Containers are made from a strong polyethylene material. These black round containers come in 3, 4, 5 and 6 feet in diameter. The ?kiddy pool? style Gro Pro? Super-Duty Saucer/Containers are perfect for use as a large saucer, a stand-alone growing container, for mixing soils or amendments and for water storage.