The silicone lid prevents splattering when microwaving and the base container is made from durable polypropylene combined with sustainably-sourced wood fiber which provides protection for the glass bowl and makes it easy to hold after microwaving. The stainless-steel lid screws onto the base to provide a leak-proof seal. -100% leakproof -Microwave safe, including wood fiber base for easy handling when hot (*not Stainless steel lid) -Oven safe glass and silicone lid (*not wood fiber base) -Dishwasher safe -BPA free 4.72in x 4.72in x 3.74in/20 fl oz.