The bowls are made of ABS plastic that is food grade and BPA free. The material allows for a durable end product. The finish on our bowls is a beautiful glossy look. The base is a TPE plastic. The TPE is a soft plastic, similar to rubber, to aid in the non-skid feature. In addition, TPE is a plastic and is overmolded to the ABS for a solid bond. The overmold makes our bowls dishwasher safe. If rubber were used, then the base would be glued and glue would breakdown after a couple of dishwasher cycles, and separate.