100% food-grade silicone material, no abnormal odor or staining; Durable, temperature resist usable for microwave, oven, freezer, easy to clean and remove. Eco-Friendly, Non-toxic, Odorless, Non-sticking, Impermeable, and Harmless. Unlike the traditional stiff plastic ice cube trays, these silicone ice sphere molds are extremely flexible and their unique design makes it easy for removing ice.