Pyrex 10pc No-leak Lid Set with Microwave Vents Leak proof and air tight seal for secure storage vents for microwaving. Set includes two 2-cup round, one 3-cup rectangular, one 4-cup round, and one 6-cup rectangular storage containers; five plastic lids. Ovensafe glass for baking Elastomer seal around plastic lid. Lid tab for easy open and close. BPA-free plastic. Made of nonporous glass that won't warp, stain, or absorb odors.